More Evidence Linking Hormone Therapy to Cancer
Elevated breast cancer risks seen in women who receive therapy for as little as three years
THURSDAY, Jan. 17 (HealthDay News) -- Despite a decrease in the use of combined estrogen and progestin hormone therapy (CHT), physicians still write 57 million hormone therapy prescriptions each year in the United States. New findings provide further evidence that CHT use -- even for as little as three years -- significantly increases the risk of invasive lobular carcinomas, according to a study published in the January issue of Cancer Epidemiology, Biomarkers & Prevention.
Christopher I. Li, M.D., of the University of Washington in Seattle, and colleagues conducted a case-control study that compared 324 lobular, 196 ductal-lobular, and 524 ductal breast carcinoma cases diagnosed between 2000 and 2004, and 469 controls aged 55 to 74.
The researchers found that current CHT users were 2.7 times as likely as non-users to develop lobular carcinomas and 3.3 times as likely to develop lobular and ductal-lobular carcinomas. The investigators observed elevated risks only in patients who had used CHT for at least three years, which is significantly shorter than the five-year figure often cited as the threshold for increased overall breast cancer risk.
"Continued research aimed at identifying the biological basis for the relationship between CHT use and lobular carcinoma risk is warranted," the authors write. "Clinically, it is important to acknowledge that lobular carcinomas tend to be less aggressive than invasive ductal carcinomas, as data indicate that lobular tumors are more likely to be estrogen receptor-positive and are associated with an 11 percent lower risk of mortality compared with invasive ductal carcinomas. Further studies focusing on the etiology of different subtypes of breast cancer are needed to advance our understanding of this heterogeneous disease."