The significant impact healthy choices have on genetic cancer risk

It can be upsetting to find out you’ve inherited a genetic mutation that makes developing certain types of cancer much more likely. Taking steps to help prevent cancer suddenly seems futile — after all, you can’t alter your genes (although science is working on that).

But as we’ve noted in earlier issues, there’s mounting evidence that following a healthy lifestyle can offer those genetically predisposed to specific cancers such as colorectal, pancreatic, breast and ovarian a surprising amount of protection against those diseases. And now, researchers are discovering the same may hold true for overall cancer risk…

Live healthy, beat cancer — despite genetics

A study published by the American Association for Cancer Research has found factors such as low body mass index (BMI), exercise and abstaining from smoking and drinking alcohol were associated with a lower incidence of cancer — even in those at high genetic risk for the disease.

Dr. Guangfu Jin, co-senior author of the study and a professor at Nanjing Medical University in China, says the study proves how important a healthy lifestyle is for people genetically predisposed toward cancer.

In recent years, researchers have developed polygenic risk scores (PRS) to arrive at a personalized estimate of an individual’s cancer risk based on certain changes in their DNA. But most PRS are generated for a specific type of cancer, not overall risk.

Jin says his team worked to create an indicator known as the cancer polygenic risk score (CPRS) to measure the genetic risk of developing all types of cancer.

Using available genome-wide association data, the researchers calculated individual PRS for 16 cancers in men and 18 cancers in women. They then employed statistical methods to combine the PRS into a single measure of cancer risk, based on the relative proportion of each cancer type in the general population. Men and women each received a separate CPRS.

For validation, the researchers took genotype information from hundreds of thousands of general-population participants in the UK Biobank and used it to calculate a CPRS for each of them. Male patients in the highest CPRS quintile were nearly twice as likely, and female patients 1.6 times as likely, to have a cancer diagnosis by the time of their most recent follow-up in 2015 or 2016.

Cancer risk follows us all

It’s interesting to note that 97 percent of patients in the study had a high genetic risk of at least one kind of cancer, which suggests almost everyone is susceptible to at least one cancer type. “It further indicates the importance of adherence to a healthy lifestyle for everyone,” Jin says.

Upon enrollment, UK Biobank participants were surveyed for various lifestyle factors, including consumption of tobacco products and alcohol, BMI, exercise habits and typical diet. The researchers used these factors to classify each patient’s overall lifestyle as unfavorable (having zero to one healthy factor) intermediate (having two to three healthy factors) or favorable (having four to five healthy factors).

Men in the highest CPRS quintile with an unfavorable lifestyle were almost three times more likely to develop cancer than those in the lowest quintile of genetic risk who followed a favorable lifestyle. For women in the highest CPRS quintile following an unfavorable lifestyle, the cancer risk was 2.38 times higher.

Among patients with high genetic risk, the five-year cancer incidence in those with an unfavorable lifestyle was 7.23 percent in men and 5.77 percent in women. That compares with 5.51 percent in men and 3.69 percent in women with a favorable lifestyle. Researchers observed similar trends in all genetic risk categories, suggesting patients could benefit from healthy lifestyle choices no matter their genetic risk.

“We hope our CPRS could be useful to improve a person’s awareness of their inherited susceptibility of cancer as a whole and facilitate them to participate in healthy activities,” Jin says.

Best practices for cancer prevention

As the study authors note, the best defense against cancer is to maintain a healthy weight, get enough exercise, refrain from smoking and limit or eliminate alcohol consumption.

Make sure your diet is centered on whole, organic, unprocessed foods and includes plenty of fish, nuts, fruits and vegetables and whole-grain fiber. Keep red meat consumption to a minimum and avoid ultra-processed meats, refined grain products and added sugars. And try to get enough calcium in your diet.

Much research has cited the importance of having healthy vitamin D levels, which helps support the immune system in protecting you from cancer. You can ask your doctor to check your blood levels of vitamin D. If your doctor advises vitamin D supplementation, they can also monitor you to make sure you’re fully responding to it.

Sources:

Healthy Lifestyle May Help Mitigate High Genetic Risk of Cancer — American Association for Cancer Research

Diet and Physical Activity: What’s the Cancer Connection? — American Cancer Society