The new data is from two randomized controlled trials known as the Women’s Health Initiative (WHI) that analyzed breast cancer incidence and deaths. The study included 27,347 women who still had their uterus and who were assigned to receive estrogen (specifically conjugated equine estrogens) plus progestin or a placebo for a median (meaning the midpoint of the range) of 5.6 years. Women who had undergone a hysterectomy were assigned to receive conjugated equine estrogen alone or a placebo for a median of 7.2 years. The study showed that after 16.1 years of follow-up, women who received estrogen alone were 27 percent less likely to have been diagnosed with breast cancer and 44 percent less like to die from the disease compared with women who received a placebo. The 44 percent reduction in breast cancer deaths is a higher rate than is seen with breast cancer prevention medications, such as tamoxifen, said Rowan T. Chlebowski, MD, PhD, the chief of the division of medical oncology and hematology at Harbor-UCLA Medical Center in Los Angeles, and an investigator at the Lundquist Institute. After 18.3 years of cumulative follow-up, women who received estrogen plus progestin were 29 percent more likely to be diagnosed with breast cancer compared with women who received a placebo. While the study participants typically used estrogen plus progestin for around five years, breast cancer risk appears to be elevated for at least 20 years and may persist for a lifetime. “The sustained effects are really remarkable. I think no one really predicted that,” Dr. Chlebowski said. Progestin is added to estrogen for women who still have a uterus to reduce the risk of endometrial cancer. But progestin appears to change breast cancer stem cells, which can give rise to cancer, said Chlebowski. Earlier findings from the WHI, in 2003, clearly demonstrated an increased risk of breast cancer associated with estrogen plus progestin and led to a 70 percent worldwide drop in use of the therapy, Chlebowski said. The new findings, showing sustained long-term risk, support that change in practice. The new findings on estrogen alone, however, conflict with findings published in September 2019 in the Lancet. That meta-analysis of 59 observational studies showed both estrogen plus progestin and estrogen alone were linked to an increased risk of breast cancer. Moreover, a study called the Million Woman Study found that both regimens increased breast cancer death. “No one has been able to reconcile these findings,” Chlebowski said. Post-menopausal women who have had hysterectomies and suffer menopausal symptoms or who have a higher-than-normal breast cancer risk should discuss the potential benefits of estrogen-only therapy, Chlebowski said. “These findings are reassuring for breast cancer risk. I think women considering estrogen alone should know it’s safe, and there may be a breast cancer benefit associated with its use.” RELATED: The Wild History of Women’s Hormone Therapy
In Other News From the SABCS…
Residual Cancer Cells Predict Long-Term Outcomes
Evidence of remaining cancer after a breast cancer patient completes surgery and chemotherapy is a useful predictor of recurrence and survival, according to a study presented December 13 at the SABCS. The study was a meta-analysis involving data from more than 5,100 patients. The authors looked at residual cancer after therapy and outcomes. The study showed that women with residual cancer were more likely to have died by 10 years of follow-up. Among patients with hormone receptor–positive and HER2-negative cancer, those with minimal residual cancer had a death rate of 14 percent compared with 48 percent of women with a high burden of residual cancer. Similar disparities in survival rates were seen with other breast cancer subtypes. “We can do a better job by having a more precise risk prediction,” said the study’s lead author, W. Fraser Symmans, MD, a professor and the director of research operations at the department of pathology at the University of Texas MD Anderson Cancer Center in Houston. RELATED: Lower-Dose Tamoxifen Is Effective at Reducing Breast Cancer Recurrence
DNA Test Could Help Predict Recurrence
A test to detect circulating tumor DNA (ctDNA) — fragments of DNA from cancer cells circulating in the bloodstream — can help predict cancer recurrence in early-stage triple negative breast cancer patients after they complete therapy, according to research from the Indiana University School of Medicine. Such a test would be extremely helpful, since women with triple negative disease have an especially high rate of relapse, says the first author of the study, Milan Radovich, PhD, an associate professor of surgery and medical and molecular genetics at Indiana University School of Medicine in Indianapolis. The study involved 142 women who underwent circulating tumor DNA testing using the FoundationOne Liquid Test. After 17.2 months of follow-up, detection of ctDNA was linked with lower disease-free survival (DDFS). Patients with ctDNA had a disease-free median survival time of 32.5 months. Patients with no detection of ctDNA had not reached the median survival at the time of the study. “We have a technology that tells us which patients do poorly,” Dr. Radovich says. The next step is to use the information to better prescribe appropriate therapy, he says. RELATED: Liquid Biopsies: What Lung Cancer Patients Need to Know
Oral Paclitaxel Works Better Than the IV Form of the Drug
An oral formulation of the chemotherapy drug paclitaxel (Taxol, Onxal) improved response and survival of patients with metastatic breast cancer compared with intravenous paclitaxel, according to a study presented December 13 at the SABCS. The phase 3 trial enrolled 402 patients who were randomly assigned to either oral paclitaxel plus encequildar or intravenous paclitaxel plus encequildar. The study showed that 51 percent of the oral paclitaxel group had a response to the drug that lasted more than 150 days compared with 38 percent of the IV group. The IV group also had higher rates of neutropenia (nerve pain), infection, and gastrointestinal side effects. Oral therapy allows patients the convenience of receiving therapy at home, said the lead author, Gerardo Antonio Umanzor Funez, MD, a medical oncologist with Centro Oncologico Integral, who conducted the study with DEMEDICA of San Pedro Sula, Honduras. A complicated oral dosing schedule may require patient education. But, he said, patients were happy to have an oral medication instead of having to go to an IV infusion center. “We were surprised that patients didn’t have a lot of issues with the medication and the regimen, said Dr. Funez. “They managed it pretty well.” RELATED: How I Live With Metastatic Breast Cancer
