• Preventive mastectomies are good for some, not for others

    Just a few weeks ago, I gushed over Peggy Orenstein’s piece in the NYT on the war on breast cancer. Today Angelina Jolie wrote an op-ed in the NYT on her decision to have a preventive mastectomy.

    I discuss this, and how it’s a very personal decision over at CNN.com.

    Go read!


    • It would be interesting to discuss the actual risk that Jolie and other people with BRCA mutations have.

      Jolie says in her op ed that her physicians estimated she had an 87% chance of developing breast cancer. However, CNN also reports that Myriad Genetics, which owns the BRCA test, is the party that gave the 87% figure. And it appears that while the BRCA2 mutation carries less risk than the BRCA1 mutation, Myriad’s figures conflate the two types: “People with a mutation in either the BRCA1 or BRCA2 gene have risks of up to 87% for developing breast cancer and up to 44% for developing ovarian cancer by age 70.”


      A 2010 article in the Journal of Clinical Oncology (ungated, below) estimated survival probabilities for women with either or no BRCA mutations. (They did a monte carlo analysis, basically a computer simulation with inputs from empirical studies on survival rates, etc). With the simulation starting at age 25, they estimated that cumulative risk of breast cancer by age 70 for BRCA 1 carriers was 65% and for BRCA 2 carriers, 45%.

      Furthermore, *without any screening, preventive mastectomy or preventive oopherectomy*, 53% of women with BRCA 1 and 71% of women with BRCA 2 survived to age 70, compared to 84% in the general female population. These are all-cause survival rates, capturing death from ovarian cancer (risk of which is increased in BRCA carriers as well) as well as from everything else. However, screening boosts survival rates to 59% and 75% for BRCA 1 and 2 carriers respectively.

      And a preventive oopherectomy (remove ovaries) at age 40 with no preventive mastectomy also boosts overall survival rate to 74% and 80% respectively. In contrast, preventive mastectomy at age 40 with no preventive oopherectomy boosts survival rates for BRCA 1 and 2 carriers to only 64% and 78%.


      Back to Myriad’s 87% figure. They’re a for-profit company which aims to sell their product. That doesn’t mean we should throw everything about their analysis out. But Stanford’s cancer center – which also has a financial incentive to sell a product, namely cancer services – says that people with a BRCA 1 mutation have an average 65% lifetime risk for breast cancer, and a 40-60% risk for a second breast cancer (not including recurrence of first cancer). Do those probabilities add up to 87%, or are Myriad’s figures off? Yes, 65% risk is high. But it’s not a certainty.

      So … I may be reading the tables wrong. This is only a simulation, albeit one based on empirically derived probabilities of cancer incidence, death, detection rates, etc. And cancer isn’t my specialty. But maybe people are mis-weighing risks. Just because you have a BRCA 1 mutation does not mean you have no symptoms at age 39 and suddenly you have stage 4 cancer at your next mammogram. You have to ask how Myriad derived its incidence rates, how they translate to actual death rates, and whether or not Jolie’s physicians were overly credulous in accepting Myriad’s estimates. You have to ask if active surveillance was an option. You have to ask if preventive chemotherapy was an option – yuck, I know, but preventive double mastectomy is definitely a major surgery as well.

      FYI, NICE does have a guideline for women with a familial pattern of breast cancer. It does not recommend routine BRCA screening. However, it does appear to recommend consideration of BRCA screening for women with a family pattern of breast cancer (which Jolie has), and it does say that preventive mastectomy is an option. It does also say that routine MRI surveillance is an option, though.