Preventive surgeries: Earlier isn’t necessarily better

17Dec09

A brand-spanking new research study to chew on while making decisions:

Survival Analysis of Cancer Risk Reduction Strategies for BRCA1/2 Mutation Carriers.

Kurian AW, Sigal BM, Plevritis SK.

PURPOSE: Women with BRCA1/2 mutations inherit high risks of breast and ovarian cancer; options to reduce cancer mortality include prophylactic surgery or breast screening, but their efficacy has never been empirically compared. We used decision analysis to simulate risk-reducing strategies in BRCA1/2 mutation carriers and to compare resulting survival probability and causes of death. METHODS: We developed a Monte Carlo model of breast screening with annual mammography plus magnetic resonance imaging (MRI) from ages 25 to 69 years, prophylactic mastectomy (PM) at various ages, and/or prophylactic oophorectomy (PO) at ages 40 or 50 years in 25-year-old BRCA1/2 mutation carriers. RESULTS: With no intervention, survival probability by age 70 is 53% for BRCA1 and 71% for BRCA2 mutation carriers. The most effective single intervention for BRCA1 mutation carriers is PO at age 40, yielding a 15% absolute survival gain; for BRCA2 mutation carriers, the most effective single intervention is PM, yielding a 7% survival gain if performed at age 40 years. The combination of PM and PO at age 40 improves survival more than any single intervention, yielding 24% survival gain for BRCA1 and 11% for BRCA2 mutation carriers. PM at age 25 instead of age 40 offers minimal incremental benefit (1% to 2%); substituting screening for PM yields a similarly minimal decrement in survival (2% to 3%). CONCLUSION: Although PM at age 25 plus PO at age 40 years maximizes survival probability, substituting mammography plus MRI screening for PM seems to offer comparable survival. These results may guide women with BRCA1/2 mutations in their choices between prophylactic surgery and breast screening.

One thing to keep in mind with this study is that it is a simulation and is not based on an actual population study. The reasons for this according to the authors is that it’s not feasible or ethical to create control groups of women with no intervention or screening-only. The numbers here are based on best available evidence of risks, but they still have to be taken with a grain of salt.

So the good news is that doing nothing (no preventive surgeries and no screening), 71% of BRCA2 carriers are calculated to live to 70. That helps me explain why so many of my relatives back on the BRCA side actually haven’t died young. Many were living well past 70 even in the 1700’s. You can compare that 71% survival rate to the 84% survival rate of the general female U.S. population. Looking at the stats this way definitely takes some of the fear out of dying young due to BRCA2. With a prophylactic oophorectomy (PO) and prophylactic mastectomy (PM), the overall survival rate to 70 for BRCA2 is 83%. Damn close to being like everyone else!

But where things get really interesting is when you look at the ages of the PO and PM. The earlier is not necessarily better. A PO at age 50 and PM at age 40 has the same survival as a PO at 40 and PM at 25: 83%! The study doesn’t even consider PO earlier than 40.

This study definitely helps lower my anxieties a bit. I was getting the impression from people’s stories that PM/PO is best done as soon as possible after testing positive. That isn’t necessarily the case for young healthy women: there may be no benefit or even possible harm in the case of PO.

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