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Chest radiation ups risk of breast cancer in young women

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Women treated with chest radiation in childhood or adolescence are at increased risk for breast cancer at a young age, and their risk does not appear to plateau over time, according to a systematic literature review in the April 6th Annals of Internal Medicine.

Regular screening for breast cancer is a must in these women, and “further research is required to better define the harms and benefits of lifelong surveillance,” senior author Dr. Kevin C. Oeffinger, from Memorial Sloan-Kettering Cancer Center, New York, and colleagues note.

Their findings stem from a systematic review of relevant studies identified through a search of MEDLINE, EMBASE, the Cochrane Library, and the Cumulative Index to Nursing and Allied Health Literature from 1966 to December 2008.

The researchers included articles that answered any of three questions: 1) What is the rate and excess risk of breast cancer in women treated with chest radiation in childhood or young adulthood? 2) What are the clinical features and treatment outcomes in such women who develop breast cancer compared with breast cancer patients in the general population? 3) What are the possible benefits and harms of breast cancer surveillance in such women?

Eleven retrospective cohort studies (with over 14,000 women) and 3 case-control studies addressed the first question. In women treated with chest radiation at a young age, the standardized incidence ratios for breast cancer ranged from 13.3 to 55.5. The cumulative rate of breast cancer by age 40 to 45 years was between 13% and 20%.

Eight studies featuring 400 women addressed the second question. Their data suggest that breast cancer characteristics of women treated with chest radiation in childhood are similar to those of women in the general population.

For the final question, the investigators used data from two retrospective studies (with 92 women) and 3 prospective studies (in 320 women). Data from these reports indicate that mammography can be used for breast cancer surveillance in the study population, although sensitivity is limited – but the benefits and harms of surveillance in this group remain unclear.

The investigators note that along with more information on the pros and cons of lifelong surveillance, research is needed to assess “how estimates of risk and outcome might change, given use of lower radiation doses in contemporary treatment.”

The study was funded by the National Cancer Institute.

Reference:

Ann Intern Med 2010;152:445-455.