Wednesday, September 14, 2011

Genetic Breast Cancers Show Up Earlier in Next Generation

 Updated 3/2017-- all links removed (except to my own posts) removed as many no longer active.

Somewhere along the line I learned to encourage women with a family history of breast cancer to begin getting mammograms at an age 10 years prior to when their mother was diagnosed and to encourage their daughters to begin getting mammograms at an age 10 years prior to when they themselves were ever diagnosed. 
I learned this prior to the discovery of BRCA genes.  It was a trend that had been noted among women with strong family histories.  The new study (see full reference below) in the journal Cancer verifies that genetic breast cancers show up earlier in the next generation – on average by 8 years.
The study from MD Anderson looked 2 generations of families with the BRCA gene to assess the age at diagnosis.  Using the pool of 132 BRCA-positive women with breast cancer who participated in the high-risk protocol at The University of Texas MD Anderson Cancer Center (Gen 2), 106 women could be paired with a family member in the previous generation (Gen 1) who was diagnosed with a BRCA-related cancer (either breast cancer or ovarian cancer).
The median age of cancer diagnosis was 42 years (range, 28-55 years) in Gen 1 and 48 years (range, 30-72 years) in Gen 2 (P < .001). In the parametric model, the estimated change in the expected age at onset for the entire cohort was 7.9 years (P < .0001). Statistically significant earlier ages at diagnosis also were observed within subgroups of BRCA1 and BRCA2 mutations, maternal inheritance, paternal inheritance, breast cancer only, and breast cancer-identified and ovarian cancer-identified families.
It is reasonable to encourage these women with significant family history of breast cancer to begin surveillance at an earlier age than the general population. 

Earlier age of onset of BRCA mutation-related cancers in subsequent generations; Litton JK, et al;  Cancer 2011; DOI: 10.1002/cncr.26284.
Breast Cancer Patients With BRCA Gene Diagnosed Almost Eight Years Earlier Than Generation Before; Science Daily, September 12, 2011
Mom's Cancer Shows Up Earlier in Daughters; Michael Smith, Dori F. Zaleznik, MD; MedPage Today, September 12, 2011


Jeannine 520 said...

It looks like the mean age in gen 2 was *older*, not younger than gen 1. Doesn't that suggest the opposite, that they're diagnosed later than their family members? Makes no sense to me, am I up too early??

rlbates said...

Jeannine, I don't have full access to the article just the abstract. I went back and reread it. I have it hear as they do in the abstract and I see what you mean. I wonder if they got the ages backwards as they conclude "Breast and ovarian cancers in BRCA mutation carriers appeared to be diagnosed at an earlier age in later generations."

Ross said...

Dr. King has a good lecture she gave at the Univ. of Washington Mini Med. School in 2010. The follow on lecture by one of the UW's genetic counselors is pretty worthwhile too. Both are accessible to an educated layperson.