Breast cancer risk not always ‘all in the family’ says study

Do you have a family member with a BRCA gene mutation and so you’re concerned about your own risk of developing cancer? Well, a new study may provide you with a reason for breathing a sigh of relief.

Stanford University researchers show that as long as you test negative for BRCA mutations, you may not have as high a risk of developing BRCA related cancer as previous studies have suggested. The mutations are associated with a significant risk of developing BRCA related breast and cervical cancer.

The study, involving more than 3,000 families, settles a four-year-old controversy that began after a study suggested that having a family member with a BRCA mutation increased BC cancer risk.

“The results are encouraging and reassuring,” said Allison Kurian, MD, lead author of the paper, which appears in The Journal of Clinical Oncology.

Dr. Kurian and her colleagues — including senior author Alice Whittemore, PhD, — said their findings support the current practice of advising BRCA non-carriers that there is no increased cancer risk just from having a family member with a BRCA mutation.

BRCA1 and BRCA2 gene mutations s are strongly associated with the development of breast or ovarian cancer: Carriers face a five- to 20-fold increased risk of developing these cancers. Female relatives without the mutation have been advised that their cancer risks are higher than women in the general population.

In 2007, however, a Journal of Medical Genetics paper showed that relatives of women with the mutation who tested negative had a two- to five-fold increased risk of developing breast cancer. Several other studies found a two-fold risk for non-carriers who had a relative with the mutation, prompting some to wonder whether breast cancer surveillance should be recommended for these family members.

“Our clinic received many calls about it — it was widely read by people in the field and by patients,” said Dr. Kurian, a practicing oncologist whose research focuses on breast cancer risks across populations. The study, and the notion that additional screening for non-carriers might be warranted, caused both concern and skepticism among cancer geneticists. “It went against what was being done.”

The 2007 study had compared relatives of BRCA carriers with women in the general population, and Dr. Kurian and her colleagues thought this might have created high estimates of the non-carriers’ risk. For one reason: Women in a family with a known BRCA mutation are more likely to receive more intensive screening, and thus be more likely to be diagnosed with breast cancer than women in the general population.

And also, said Dr. Whittemore, “First-degree [or close] relatives of breast cancer patients are themselves at higher risk than women in the general population. So some reports of higher risk among non-carriers, as compared to risk in the general population, may have been an inappropriate comparison of apples and oranges.”

The researchers sought, then, to compare cancer risk in non-carriers with a control group of relatives of cancer patients without the mutations. For the study they used data from population-based cancer registries to look at 3,047 families. Of the total, 160 families had BRCA1 and 132 families had BRCA2 mutations.

When comparing the groups of relatives, they found no evidence of an increased breast cancer risk for non-carriers.

The findings should put to rest questions about risk based on a familial BRCA mutation. But Dr. Kurian added, “It’s important for patients and clinicians to remember this doesn’t rule out other risk factors, which might increase a non-carrier’s probability of getting breast cancer.”

Sidebar: BRCA Mutations, Men, and Cancer

By Healthy Living News

Can men have BRCA mutations and will they increase cancer risk? Well — yes and yes. Although they don’t seem to increase a man’s cancer risk as much as they do a woman’s. But they still can significantly increase a man’s chance of developing breast cancer, prostate cancer, skin cancer and a few other types of cancers. Particularly if they have the BRCA2 mutation. BRCA mutations also make it more likely cancer will occur at a younger age. So, men from families with a history of cancer should consider testing for BRCA gene mutations, particularly if a family member got cancer before age 50. As should men who have already had cancer but never got tested for the mutations.

Courtesy of Healthy Living News

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