Get used to new paradigm for treating breast cancer

February 20, 2006

To commemorate its 50th anniversary, the Avon Foundation recently sponsored a global research symposium in New York City titled "Breast Cancer 2005: From Discovery to Delivery." There were a number of significant takeaways from the meeting.

Valerie Beral, M.D., director of cancer research, University of Oxford, presented a global summary of breast cancer epidemiology and focused on the role of early birth and breast-feeding as key breast cancer risk reduction components. Research to date has focused on the role of estrogen and progestin in the etiology of breast cancer, but, Beral wondered if ... "perhaps there are other areas researchers should be looking at, such as prolactin?"

In response, Paul Goss, M.D., Ph.D., director of breast cancer research at Massachusetts General Hospital and professor of medicine at Harvard Medical School, pointed out that there is research demonstrating that a woman's breasts are not fully conditioned until they experience childbirth and breast-feeding. Perhaps, he said, finding ways to simulate pregnancy and lactation through artificial means might ultimately reduce breast cancer risk.

From Goss' perspective, "the two biggest spectacle events in the last decade were the advent of aromatase inhibitors and, now, possibly Herceptin [trastuzumab, Genentech]. Although the result from the Herceptin study is very profound, the follow-up is short, and also it was done in a minority of breast cancer patients. Only 20% of women have Her2-positive breast cancer, although, in fairness, it is a disproportionate cause of mortality. So it is an important discovery."

Goss would like to see further improvement of endocrine therapy, more durable therapy, and further understanding of the relapse risk associated with breast cancer therapy. With regard to the latter, he presented data showing that although estrogen-receptor negative (ER–) breast tumors (relative to estrogen-receptor positive [ER+] breast tumors) are more difficult to treat in the first five years after diagnosis, over the long term, the mortality and morbidity associated with both types may be quite similar, given the much higher post-five-year relapse rate seen with ER+ tumors.

Goss noted that global breast cancer data available two weeks prior to the meeting from the Oxford Epidemiological Group found that "if you look at the 15-year breast cancer-specific mortality rate from time of diagnosis in receptor-positive versus receptor-negative [tumors], it's equal...." The implications for long-term therapy for ER+ breast tumors are quite dramatic.

The current operating paradigm of "if you get past the initial five years, you're safe, no longer holds true," and "we need a reliable long-term outcomes database that tells us the natural history of this disease," Goss said. He envisioned that clinical trials going forward will be designed in a way that supplements the available data from tumor registries, allowing for segmentation of breast cancer patients and specification of drug "cocktails" targeted to specific tumor types.

Clifford Hudis, M.D., Ph.D., chief of the Breast Cancer Medicine Service at Memorial Sloan-Kettering Cancer Center, focused on developments in chemotherapy for breast cancer and discussed a variety of trials that have been completed or are under way. He noted that perhaps one of the most significant developments over the past decade has been the emergence of supportive erythropoietin therapy, which allows for more rapid cycling of the various cytotoxic chemotherapeutic agents and, potentially, leads to higher cure rates.

In a follow-up interview, John Forbes, R.Ph., a community pharmacist at Medicap pharmacy in Des Moines, noted, "Lately, we are seeing more physicians moving away from tamoxifen and using Arimidex [anastrozole, AstraZeneca]." He believes "we will see more drugs targeted toward post-treatment of breast cancer. And pharmacists will play a large role in [establishing] the correct usage of these drugs."

THE AUTHOR is a healthcare communications specialist residing in Montville, N.J.