Lynch syndrome: a three-fold increase in cancer risk

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What is Lynch syndrome?

Lynch syndrome is a hereditary cancer-predisposition syndrome that significantly increases the likelihood of developing several different cancers at an earlier age than typically expected, and can affect males and females.

Lynch syndrome doesn’t present with any physical manifestations and is usually suspected following a cancer diagnosis or in individuals with a significant family history of Lynch syndrome-related cancers. The diagnosis is confirmed through genetic testing. While the uncertainty of genetic predisposition can be daunting, understanding Lynch syndrome and the steps available to manage the risks can be empowering.

What causes Lynch syndrome?

It’s caused by inherited mutations in one of several genes responsible for repairing DNA errors: MLH1, MSH2, MSH6, PMS2, or EPCAM. An inherited mutation can disrupt this repair process, allowing errors to accumulate, eventually leading to cancer.

Lynch syndrome is most associated with colorectal and endometrial cancers. However, it also increases the risk for ovarian, gastric, urinary tract, small bowel, and pancreatic cancer. Knowing the causative mutation provides critical insights into specific risks and helps guide cancer screening and prevention.

Risks vary by gene

One of the most challenging aspects of Lynch syndrome is its variability. Cancer risks differ based on the specific mutation and between men and women, making personalised management essential.

Mutations in MLH1 and MSH2 are linked to the highest lifetime cancer risks: a 40–50% risk of colorectal cancer, compared to the ~2% risk in the general population; a 35–45% risk for endometrial cancer; and 10–20% risk for ovarian cancer.

In contrast, mutations in MSH6 and PMS2 carry lower, though still significant, cancer risks. They are associated with a later onset of colorectal cancer, but women with MSH6 mutations have the same risk for endometrial and ovarian cancers as those with MLH1 and MSH2 mutations.

Screening: the life-saving power of early detection

Early detection is one of the most powerful tools if you have Lynch syndrome. Once diagnosed through genetic testing, patients are eligible for intensive cancer screening programmes.

For colorectal cancer, colonoscopies are recommended every 1–2 years, starting at 20–25 years old or five years before the youngest diagnosed family member. This helps detect precancerous polyps or early-stage cancers, which are far easier to treat. Additionally, aspirin may be prescribed, as research suggests this may lower colorectal cancer risk.

For endometrial cancer, screening includes annual endometrial sampling starting at 30–35 years old. No reliable screening exists for ovarian cancer, though CA-125 blood tests may help monitor risks. Screening plans are tailored to the individual, their mutation, and family history to ensure the most thorough surveillance.

Screening recommendations, however, continue to evolve with advancing research, so it’s essential to maintain close communication with a knowledgeable healthcare team.

Prophylactic surgery: reducing risk further

For some, surveillance alone may not be sufficient to mitigate the cancer risk. In such cases, prophylactic (preventive) surgery may offer additional protection.

Women with Lynch syndrome who have completed childbearing often consider a prophylactic hysterectomy (removal of the uterus) and bilateral oophorectomy (removal of the ovaries) to dramatically reduce their risk for both endometrial and ovarian cancers. The decision to undergo surgery though deeply personal can offer life-changing peace of mind.

Knowledge and family: The foundation of empowerment

A diagnosis of Lynch syndrome can be overwhelming, but it also opens the door to proactive health management. Children, siblings and parents all have a 50% chance of inheriting the causative mutation. Family testing can identify affected members, allowing you to take proactive and preventive action, often prior to developing cancer.

Embracing a proactive approach to health allows families to gain control over the unknown and while Lynch syndrome can’t be cured, early diagnosis and preventive measures save lives.

It’s important to remember that if you have Lynch syndrome, you’re not alone. Support is available through healthcare teams, genetic counselling services, and patient organisations. These resources not only offer guidance but also connect families navigating similar journeys.

By staying informed, vigilant, and supported, individuals with Lynch syndrome can live full, healthy lives while significantly reducing their cancer risks.