HRT & Breast Cancer

HRT Users With Breast Cancer Had Smaller Tumors Than HRT Nonusers

North American Menopause Society19th Annual Scientific Meeting

New data reveal that women diagnosed with breast cancer while using hormone therapy had smaller tumors and an earlier stage of breast cancer, compared with their non-using peers. The researchers also reported a higher five-year survival rate for women with breast cancer using HT.

Jing-Hong Kim, MD, and Mee-Ran Kim, MD, obstetrician/gynecologists at The Catholic University of Korea, conducted a study to determine associations between HT use and prognostic indicators of breast cancer among postmenopausal women who had and had not been treated with HT. Using medical records between 1995 and 2004, the researchers collected data on various characteristics, such as age at diagnosis and menopause, method of treatment, size of tumor and mortality rate.

Women using HT had a higher operative menopause rate of 41.38% compared with 16.84% among non-users (P=.0014). HT users also had a higher well differentiation rate compared with non-users — 53.85% vs. 13.36% (P=.0026).

More than half (55.17%) of women treated with HT had tumors in stage T1 or lower compared with 28.57% of women who did not take hormones.Women using HT also had smaller tumors than nonusers (P=.0032).

These findings were presented at the North American Menopause Society 19th Annual Scientific Meeting in Orlando by Katie Kalvaitis

It is interesting that researchers in Korea are finding the same thing we have found in our American studies. A number of observational studies have shown that women on hormones have a less invasive, more easily curable cancer. It's thought that the reason is that the hormones are acting as a promoter rather than a cause, and cancers in these women may be picked to operate early because of increased surveillance. The interesting thing is that these data run contrary to what was seen in the Women's Health Initiative, in which researchers reported more invasive, larger cancers that weren't estrogen-receptor positive in the treated estrogen plus progestin arm. There is a dichotomy there that is not well-explained.

Michelle P. Warren, MD
Endocrine Today Editorial Board member