Lynch syndrome is a genetic condition that raises the risk of certain cancers, especially colorectal and uterine cancer. Many people with Lynch syndrome feel well for years, and there are usually no early symptoms of Lynch syndrome until a cancer develops. It is lifelong and often identified in adulthood, but it can be recognized earlier in families with a pattern of young-onset cancers. Regular screening, removal of precancerous polyps, risk-reducing surgery in select cases, and genetics-informed care are the main treatments. Cancer risk depends on the specific gene and family history, and with close surveillance many people with Lynch syndrome live long and full lives.
Overview
Lynch syndromeSymptoms
Lynch syndrome usually causes no symptoms until a related cancer develops. Warning signs can include bowel habit changes, rectal bleeding, belly pain, unexplained anemia, or abnormal uterine bleeding. Clues include early cancers in one person and a strong family history.
Outlook and prognosis
Most people with Lynch syndrome live full lives, especially with regular screening and prompt treatment of any findings. Early and ongoing colonoscopies and checks for uterine, ovarian, stomach, and urinary cancers greatly lower risk and improve survival. Family planning, genetic counseling, and tailored prevention plans help many feel prepared and protected.
Causes and risk factors
Lynch syndrome stems from inherited changes in DNA repair genes, most often passed from a parent; new changes are uncommon. Risk rises with a family history of early colorectal or endometrial cancer; smoking, obesity, and processed meats may add risk.
Genetic influences
Genetics are central in Lynch syndrome. Inherited variants in DNA repair genes greatly raise lifetime risks for colorectal, endometrial, and some other cancers. Family testing helps identify relatives at risk and guides earlier, more frequent screening and risk‑reducing care.
Diagnosis
Doctors review personal and family cancer history, then test tumors for mismatch repair problems. A germline multigene panel confirms the genetic diagnosis of Lynch syndrome. Relatives may be offered cascade testing after a pathogenic variant is found.
Treatment and drugs
Treatment for Lynch syndrome focuses on early detection and prevention. Care often includes regular colonoscopies, removal of precancerous polyps, risk‑reducing surgery for some, and tailored screening for uterus, ovary, stomach, urinary tract, and skin. Doctors may recommend aspirin and discuss immunotherapy if cancer develops.
Symptoms
People with Lynch syndrome often feel healthy for years, because it raises the chance of certain cancers rather than causing ongoing symptoms. Early features of Lynch syndrome usually show up as patterns—cancer at a younger age, more than once in the same person, or several relatives with related cancers. A healthcare professional can help sort out what’s typical aging and what warrants a closer look. Knowing these signs can guide screening and genetic testing.
People may develop colorectal cancer at a younger age than expected, often before 50. You might notice blood in the stool, ongoing changes in bowel habits, or unexplained anemia.
Endometrial (uterine) cancer can occur earlier in people with Lynch syndrome. Warning signs include bleeding after menopause or between periods.
Ovarian cancer risk is higher and may occur at younger ages. Bloating, pelvic pain, feeling full quickly, or urinary urgency can be subtle and easy to miss.
Some people develop more than one primary cancer over their lifetime, such as colorectal plus uterine or ovarian cancer. This pattern is consistent with Lynch syndrome but can appear in other conditions too.
How people usually first notice Lynch syndrome?
Many people first notice Lynch syndrome not because of early symptoms, but because a close relative is diagnosed with colorectal or endometrial cancer at a young age, prompting family discussions or genetic testing. Others learn about it after a colon polyp or cancer is found earlier than expected during a routine colonoscopy, or when a pathology report shows features that suggest a DNA mismatch repair problem. If a relative’s tumor is tested and shows mismatch repair deficiency or microsatellite instability, doctors often recommend genetic counseling and testing for the family to check for Lynch syndrome.
Types of Lynch syndrome
Lynch syndrome has several well-recognized variants based on which mismatch repair gene is affected. These variants tend to raise lifetime risks for certain cancers in different ways, and they can vary in the average age cancers show up. People may notice different sets of symptoms depending on their situation. When reading about types of Lynch syndrome, you’ll often see the gene name used to label the variant; knowing the gene can help predict which organs are most at risk.
MLH1-related
This variant carries a higher overall risk for colorectal and endometrial cancers. Ovarian, stomach, and small bowel cancers can also occur.
MSH2-related
Cancer risks are similar to MLH1, with a strong risk for colorectal and endometrial cancer. Urinary tract and skin adnexal tumors are somewhat more common than with other genes.
MSH6-related
Colorectal cancer risk is elevated but often starts later on average. Endometrial cancer risk is high, and some people present with uterine cancer before colon changes.
PMS2-related
This is generally associated with lower, later-onset risks compared with other Lynch genes. Colorectal and endometrial cancer can still occur, often at older ages.
EPCAM deletion
Deletions near EPCAM can silence MSH2 and act like MSH2-related Lynch. People may have similar risks, especially for colorectal and endometrial cancers.
Constitutional MMR deficiency
When two faulty copies are inherited, childhood cancers can develop across the brain, blood, or gastrointestinal tract. This rare condition is distinct from typical types of Lynch syndrome and presents much earlier.
What genetics can tell you about symptoms
Certain gene changes in MLH1, MSH2, MSH6, PMS2, or EPCAM raise the chance of early colorectal or endometrial cancer, often without many warning symptoms besides occasional bleeding, anemia, or bowel habit changes. MSH6 and PMS2 variants often show later, milder patterns than MLH1 or MSH2.
Causes and risk factors
Lynch syndrome is caused by a harmful change in a DNA repair gene such as MLH1, MSH2, MSH6, PMS2, or EPCAM.
It is usually inherited, so a parent with Lynch syndrome has a 50% chance of passing it to each child.
Key risk factors for Lynch syndrome include a family history of early colorectal or endometrial cancer and multiple relatives with related cancers, and cancer risk varies by which gene is affected, age, and sex.
Genes set the stage, but environment and lifestyle often decide how the story unfolds.
In people with Lynch syndrome, smoking, diets high in processed meats, obesity, and H. pylori infection can raise cancer risk, while a healthy weight, regular exercise, and doctor-guided aspirin may lower colorectal cancer risk.
Environmental and biological risk factors
People often ask what raises the chance of having Lynch syndrome in a family. There are usually no early symptoms of Lynch syndrome, so the focus here is on what can make it occur in the first place. Doctors often group risks into internal (biological) and external (environmental). For this condition, most risk comes from rare events around conception, and links to everyday environmental exposures are limited.
Having an older father at conception slightly raises the chance of a new DNA change in the sperm. This remains a rare event.
Rare, chance errors during formation of egg or sperm can lead to Lynch syndrome even without family history. These events are uncommon.
In rare cases, a parent carries the change only in some reproductive cells, so routine blood testing may not show it. This can increase the chance of Lynch syndrome appearing again in siblings.
Prior high-dose radiation to the testes or ovaries can damage reproductive cell DNA. This could slightly raise the chance of a new change in a future pregnancy, though a direct link to the syndrome is unproven.
Genetic risk factors
If close relatives have had colorectal or uterine cancer at a young age, a hereditary cause may be involved. In many families, this pattern is due to Lynch syndrome, driven by changes in genes that normally fix DNA mistakes. Carrying a genetic change doesn’t guarantee the condition will appear. There are often no early symptoms of Lynch syndrome, so family history and genetic testing can be key.
MLH1 variants: Changes in the MLH1 gene are a common cause of Lynch syndrome. They often bring higher lifetime risks and earlier ages for colorectal and uterine (endometrial) cancers.
MSH2 variants: MSH2 changes also account for many Lynch syndrome cases. They can raise risk for colorectal, endometrial, and urinary tract cancers.
MSH6 variants: MSH6 changes generally lead to later-onset cancers. Risk for uterine cancer can be substantial, while colorectal risk is often lower than with MLH1 or MSH2.
PMS2 variants: PMS2 changes usually carry lower average risks. Cancers often appear later in adulthood, and some people never develop a Lynch-related cancer.
EPCAM deletions: Deletions at the end of the EPCAM gene can switch off the neighboring MSH2 gene. This causes Lynch syndrome with a risk pattern similar to MSH2 changes.
Dominant inheritance: Lynch syndrome is inherited in an autosomal dominant way: one altered copy is enough to raise risk. Each child of an affected parent has a 50% (1 in 2) chance to inherit the gene change.
Family history: Having a first-degree relative with a proven DNA repair gene change strongly increases your own chance of carrying it. Multiple relatives with colorectal, uterine, or related cancers—especially before age 50—also point to higher genetic risk.
De novo changes: Rarely, a new gene change arises in someone with no family history. In that case, siblings usually have low risk unless a parent is found to carry the same change.
Variable penetrance: Not everyone with a Lynch gene change will develop cancer. The level of risk and the types of cancer vary by which gene is affected and by sex and age.
Tumor clues: Tumor testing that shows missing DNA repair proteins or high microsatellite instability can point to inherited Lynch syndrome. These findings can guide doctors to recommend germline genetic testing.
Lifestyle risk factors
Lifestyle choices do not cause Lynch syndrome, but they can influence cancer risks, age of onset, and recovery from treatment. Research is ongoing on how lifestyle affects Lynch syndrome, so recommendations lean on cancer-prevention data applied to this higher-risk context. Focus on changes that plausibly lower colorectal and related cancer risks while supporting screening and treatment tolerance.
A plant-forward diet rich in fiber, whole grains, legumes, fruits, and vegetables may lower colorectal cancer risk in people with Lynch syndrome. Limiting ultra-processed foods supports a healthier gut environment that may reduce inflammation in the colon.
Frequent intake of red and processed meats is linked to higher colorectal cancer risk and may add to the already elevated risk in Lynch syndrome. Choosing fish, poultry, or plant proteins more often can reduce exposure to carcinogenic compounds formed during processing and high-heat cooking.
Regular alcohol use raises risks for colorectal and certain other cancers and can compound Lynch syndrome–related risk. Keeping alcohol within low-risk guidelines or avoiding it may help reduce cumulative cancer risk.
Smoking increases colorectal and upper gastrointestinal cancer risk and in Lynch syndrome may be linked to earlier cancer onset. Quitting reduces exposure to carcinogens that can accelerate tumor development in mismatch-repair–deficient tissue.
Risk prevention
Lynch syndrome can’t be prevented, but you can lower cancer risks and catch problems early. Prevention focuses on regular screening, considering certain medications or surgeries, and building everyday habits that protect long‑term health. Plans differ by age, gene change, family history, and personal goals. Different people need different prevention strategies—there’s no single formula.
Start earlier and repeat more often than the general public, typically every 1–2 years starting in early adulthood. This helps find and remove polyps before they turn into cancer.
Some people with Lynch syndrome may lower colorectal cancer risk by taking daily aspirin. Ask your doctor about dose, timing, and bleeding risks before starting.
For people with a uterus, report abnormal bleeding right away and discuss periodic checks. Early attention can find uterine cancer at a more treatable stage.
After completing family plans, some choose hysterectomy and removal of ovaries/tubes to prevent uterine and ovarian cancers. This option lowers risk but has long‑term effects that need careful counseling.
Transmission
Lynch syndrome is not contagious and cannot be passed through everyday contact. It runs in families because of a change in one copy of a DNA repair gene; a parent with Lynch syndrome has a 50% chance of passing that change to each child (a pattern called autosomal dominant). In a small number of people, the gene change occurs for the first time, so Lynch syndrome appears without a known family history. If Lynch syndrome is in your family, talking with a genetics professional about how Lynch syndrome is inherited can guide decisions about testing and cancer screening for relatives.
When to test your genes
Consider genetic testing if colon or uterine cancer runs in your family, especially with diagnoses before age 50, multiple related cancers, or several relatives across generations. Test if you’ve had colorectal, endometrial, or certain GI/urinary cancers—results can guide screening, surgery, and medication choices. A genetics professional can tailor timing and which genes to include.
Diagnosis
Lynch syndrome is usually diagnosed by putting together clues from your personal and family cancer history and then confirming with specific tests. Some conditions have a genetic link, meaning they can run in families. Doctors often start with patterns—such as colon or uterine cancer at a younger age—and then look for tumor features that point toward this hereditary syndrome. Genetic testing can then confirm the diagnosis with more certainty.
Your provider reviews which relatives had cancer and at what ages. Clusters of colon, uterine, or related cancers—especially before age 50—raise suspicion for Lynch syndrome. This guides which tests come next.
Early colorectal or endometrial cancer, or more than one primary cancer in the same person, are red flags. Tumors on the right side of the colon are also more common in Lynch syndrome. These features help prioritize testing.
Labs can examine a biopsy or surgical tumor sample for signs of a DNA repair problem. Abnormal results suggest Lynch syndrome and prompt inherited genetic testing. These tests do not by themselves confirm an inherited cause.
Pathologists may check for the presence or absence of mismatch repair proteins using special stains. Loss of one or more of these proteins supports possible Lynch syndrome. It also helps target which gene to test in the blood or saliva.
Stages of Lynch syndrome
Lynch syndrome does not have defined progression stages. It’s a genetic condition that raises lifetime risks for certain cancers rather than moving through set phases, and there are often no early symptoms of Lynch syndrome itself. Doctors look at family history, test tumor samples for mismatch repair changes, and confirm with a blood or saliva genetic test, while monitoring relies on regular screening such as earlier and more frequent colonoscopy and, for many, gynecologic and other organ-specific checks. Genetic testing may be offered to clarify certain risks.
Outlook and prognosis
Day to day, many living with Lynch syndrome focus on staying ahead of risks through regular screening rather than coping with constant symptoms. Early care can make a real difference, especially because most cancers linked to Lynch syndrome are highly treatable when found early. Doctors call this the prognosis—a medical word for likely outcomes. With recommended colonoscopies, uterine and ovarian assessment when relevant, and attention to stomach and urinary tract health, many people maintain normal life expectancy.
Looking at the long-term picture can be helpful. The chance of developing certain cancers is higher with Lynch syndrome, but the exact risk depends on which gene is involved, age, sex, family history, and preventive steps taken. In medical terms, the long-term outlook is often shaped by both genetics and lifestyle. When cancers are caught early through screening, survival rates are strong; for example, early-stage colon cancer is often cured with surgery, and some choose preventive surgery to reduce uterine or ovarian cancer risk.
Everyone’s journey looks a little different. Some people experience early symptoms of Lynch syndrome–related cancers like changes in bowel habits or unexpected bleeding, while others notice no signs until screening picks up a concern. Mortality varies with cancer type and stage at diagnosis, but regular surveillance lowers the chance of late-stage disease and cancer-related death. Talk with your doctor about what your personal outlook might look like.
Long-term effects
Lynch syndrome increases lifetime risks for several cancers, often at younger ages than average. Long-term effects vary widely, depending on the specific gene involved and family patterns. Many live for years without symptoms, but the main concerns are colorectal, uterine, and ovarian cancers, along with a smaller increase in certain other tumors.
Cancers linked to Lynch syndrome tend to appear earlier than in the general population. For many, diagnoses occur in adulthood, sometimes before age 50. Risks continue across the lifespan.
Lifetime risk is higher than average for colon and rectal cancer. Tumors can develop from polyps more quickly than usual. Some people have multiple colon cancers over time.
People with a uterus face a higher risk of endometrial (uterine) cancer. This may be the first cancer diagnosed in some. Abnormal bleeding can be an early clue.
Risk of ovarian cancer is increased compared with the general population. For many, risk rises in mid-adulthood. Some may develop more than one primary cancer over time.
How is it to live with Lynch syndrome?
Living with Lynch syndrome often means planning with a longer view: regular colonoscopies, periodic checks of the uterus and ovaries for some, and conversations about risk-reducing options at ages when friends may not be thinking about cancer at all. Day to day, most people feel physically well; the challenge is scheduling screenings, keeping track of family history, and managing the steady hum of “what if,” which usually quiets when a clear plan is in place. Partners, relatives, and children may feel ripple effects—worry, extra appointments, and sometimes genetic testing decisions of their own—but many families find that sharing information, setting reminders, and leaning on a care team turns vigilance into routine. Over time, people often become skilled advocates for themselves and their loved ones, balancing prevention with a full, ordinary life.
Treatment and drugs
Treatment for Lynch syndrome focuses on lowering cancer risk and finding cancer early, since this condition raises the chance of colon, uterine, and several other cancers. Care usually includes regular screening starting at a younger age and done more often than average, such as colonoscopies every 1–2 years, plus gynecologic screening and discussions about preventive surgery for those at higher risk or done having children. Some people consider risk-reducing surgery, like removing the uterus and ovaries after family planning, to sharply cut the chance of uterine and ovarian cancer. Treatment plans often combine several approaches, including genetic counseling, lifestyle measures, and—when needed—medicines to prevent or treat cancer, such as aspirin for colorectal risk reduction or immunotherapy for cancers that arise. Ask your doctor about the best starting point for you, and revisit the plan over time as your needs change.
Non-drug treatment
Living with Lynch syndrome often means staying a step ahead of cancer risk through planned checkups, tailored screening, and informed family decisions. Non-drug treatments often lay the foundation for staying ahead of cancer risk. These approaches include regular colonoscopies, gynecologic planning, genetic counseling, and healthy lifestyle habits, adjusted to your age, gene change, and family history.
Regular colonoscopy, often every 1–2 years starting in early adulthood or earlier based on family history, finds precancerous changes. Removing polyps lowers colorectal cancer risk in Lynch syndrome. Your care team may adjust the interval after each exam.
After finishing family planning, hysterectomy with or without ovary removal can lower uterine and ovarian cancer risks in Lynch syndrome. Discuss timing, menopause effects, and personal risk. Planning with a gynecologic oncologist helps tailor choices.
If delaying surgery, options may include yearly endometrial sampling and transvaginal ultrasound. These tests do not prevent cancer but can catch changes earlier. Seek care promptly for any abnormal uterine bleeding.
Upper endoscopy at intervals may be advised for some people with Lynch syndrome, especially with certain gene changes or family history. It examines the stomach and first part of the small intestine. Your doctor will individualize timing.
Your genes may have an impact on how drugs work for you
Drugs used for Lynch syndrome, like chemotherapy or immunotherapy, can work differently because enzyme and immune-related genes vary from person to person. Pharmacogenetic testing can sometimes guide dosing or drug choice to boost benefit and reduce side effects.
Pharmacological treatments
For people living with Lynch syndrome, medicines play two roles: lowering cancer risk and treating cancers if they arise. You might picture medicine as one tool among many—alongside regular screening and, for some, risk-reducing surgery. Aspirin for Lynch syndrome prevention has the strongest evidence among drugs used to reduce colorectal cancer risk. When cancers related to Lynch syndrome develop, modern immunotherapy and standard chemotherapy are commonly used, depending on the cancer type and stage.
Daily low‑dose aspirin can lower the risk of colorectal cancer over time. Decisions about starting, dose, and duration depend on age, bleeding risk, and personal/family history.
Combined oral contraceptives and the levonorgestrel IUD can reduce endometrial cancer risk, with possible benefit for ovarian cancer risk. These options may suit people who also want contraception or menstrual control.
Pembrolizumab or nivolumab, alone or with ipilimumab, can shrink mismatch‑repair–deficient or MSI‑high cancers linked to Lynch syndrome. These drugs help the immune system recognize and attack tumor cells.
Standard regimens like 5‑fluorouracil, capecitabine, and oxaliplatin are used when chemotherapy is needed. In some early MSI‑high colon cancers, chemotherapy may add limited benefit, so plans are individualized.
Genetic influences
In most families, Lynch syndrome results from an inherited change in one of the genes that normally repair everyday DNA mistakes, which raises lifetime risk for certain cancers. These genes—such as MLH1, MSH2, MSH6, PMS2, or EPCAM—act like quality-control checks; when one isn’t working, cells can collect errors and are more likely to become cancerous. Lynch syndrome is passed down in families, so each child of someone who carries the gene change has a 1 in 2 (50%) chance to inherit it. Family history is one of the strongest clues to a genetic influence. Still, inheriting the gene change raises risk but doesn’t guarantee you’ll develop cancer, and the age and types of cancer can vary widely even within the same family. Understanding the genetic causes of Lynch syndrome can guide care: genetic testing can find the specific change, and knowing your result can shape screening plans for you and your relatives.
Is Lynch syndrome genetic?
Genetics are central in Lynch syndrome. Inherited variants in DNA repair genes greatly raise lifetime risks for colorectal, endometrial, and some other cancers. Family testing helps identify relatives at risk and guides earlier, more frequent screening and risk‑reducing care.
Pharmacogenetics—how genetics influence drug effects
The inherited DNA repair change that causes Lynch syndrome can also shape treatment choices when cancer develops. Tumors linked to Lynch often carry many DNA changes and a repair problem, which makes them more likely to respond to immunotherapy drugs that help the immune system see and attack the cancer. Traditional chemotherapy may still be used, but the way your body breaks down certain drugs can vary based on genes you were born with. Genetic testing can sometimes identify how your body processes drugs like 5‑fluorouracil (5‑FU) or capecitabine and irinotecan, helping doctors adjust the dose to improve safety. This kind of testing can reduce the chance of severe side effects and may prevent delays in treatment by guiding dosing from the start. Aspirin is sometimes recommended to lower colorectal cancer risk in Lynch syndrome; at this time, genes do not guide aspirin dose, so decisions are based on your age, bleeding risk, and plans you make together with your care team. Other factors like the cancer’s stage, your overall health, and the other medicines you take also play a role in treatment choices.
Interactions with other conditions
For people with Lynch syndrome, having another condition can change cancer risks and the timing of screening. A chronic stomach infection with Helicobacter pylori may add to the risk of stomach cancer in Lynch syndrome, so testing and treatment to clear it can be considered as part of care. If someone also lives with inflammatory bowel disease, ongoing gut inflammation can further raise colorectal cancer risk, and doctors may advise colonoscopies more often than the usual Lynch syndrome schedule. Smoking increases the chance of urinary tract cancers; in Lynch syndrome, this can compound an already higher baseline risk. People who need long-term immune‑suppressing medicines, such as after an organ transplant, may face earlier or faster‑growing cancers, so follow‑up is usually closer in this situation. Talk with your doctor about how your conditions may influence each other.
How genes can cause diseases
Humans have more than 20,000 genes, each carrying out one or a few specific functions in the body. One gene instructs the body to digest lactose from milk, another tells the body how to build strong bones and another prevents the body's cells from beginning to multiply uncontrollably and developing into cancer. As all of these genes combined are the building instructions for our body, a defect in one of these genes can have severe health consequences.
Through decades of genetic research, we know the genetic code of any healthy/functional human gene. We have also identified that in certain positions on a gene, some individuals may have a different genetic letter from the one you have. We call these hotspots "Genetic Variations" or "Variants" in short. In many cases, studies have been able to show that having the genetic letter "G" in the position makes you healthy, but having the letter "A" in the same position disrupts the gene function and causes a disease. Genopedia allows you to view these variants in genes and summarizes all that we know from scientific research, which genetic letters (Genotype) have good or bad consequences on your health or on your traits.
History
Throughout history, people have described families in which several relatives developed bowel or womb cancers at relatively young ages. A grandparent lost to “stomach trouble,” an aunt with colon cancer in her 40s, a cousin needing frequent screenings—patterns like these stood out long before doctors understood why. Family doctors and surgeons began noting these clusters in clinic notes and hospital logs, recognizing that some cancers seemed to run together across generations.
From early theories to modern research, the story of Lynch syndrome moved from careful observation to genetic insight. In the mid-20th century, researchers documented families with multiple cases of colorectal and endometrial cancers, sometimes alongside cancers of the ovary, urinary tract, small intestine, or stomach. These reports shaped the first clinical rules for spotting high-risk families, based on who was affected, at what age, and how many relatives were involved.
Initially understood only through symptoms, later the condition was linked to a missing safeguard inside our cells. In the 1990s, scientists discovered that people with Lynch syndrome carry changes in genes that perform “mismatch repair,” a built‑in proofreading system for DNA. When this system is weakened, cells collect errors more quickly, raising the chance of certain cancers. This finding transformed the field: it explained the family patterns, allowed for genetic testing, and led to tumor tests that could flag who should consider further evaluation.
As medical science evolved, the name also shifted. Earlier labels focused on colon cancer alone, but “Lynch syndrome” came to reflect the broader range of related cancers and the inherited nature of the condition. With each decade, guidelines improved, expanding beyond strict age cutoffs to include tumor features and molecular tests. This meant more people at risk could be identified, including those without striking family histories.
In recent decades, awareness has grown as screening colonoscopy, preventive gynecologic care, and tailored surveillance have been shown to lower cancer risk and catch cancers earlier for many living with Lynch syndrome. Treatment advances followed, too. The same DNA repair changes that help diagnose the condition also predict which cancers may respond to certain immunotherapies, giving people more options.
Looking back helps explain why today’s approach emphasizes both family story and biology. The path from observed cancer clusters to gene discovery and practical care has been steady and collaborative. Each stage in history has added to the picture we have today, allowing families to move from uncertainty to informed choices about testing, screening, and prevention.