Debra A. Patt, MD, MPH, MBA, FASCO

Debra A. Patt, MD, MPH, MBA, FASCO, Clinical Professor at Dell Medical School at The University of Texas at Austin and Executive Vice President of Public Policy and Strategy Initiatives for Texas Oncology, told attendees in a symposium highlights talk, “We all identify and follow some patients who are at high risk, and we’ve all told them how chemoprevention can help reduce risk over time. Two large trials—MAP.3¹ and IBIS-II²—showed benefit for this strategy, and now the long-term follow-up of IBIS-II asked whether patients continue to have risk reduction long after chemoprevention.”

She continued: “With 12 years of follow-up, there was a risk of breast cancer of 8.8% in the nonintervention group and 5.3% in the intervention group, so obviously, there continues to be a benefit…. And it is substantial. It’s nearly half the risk,” she noted. “In addition, what surprised me was the 28% statistically significant reduction in the incidence of all cancers. This warrants further follow-up.”

Prevention Therapy Underutilized

C. Kent Osborne, MD, FASCO

C. Kent Osborne, MD, FASCO, Director of the Dan L Duncan Comprehensive Cancer Center, Professor of Medicine, and the Dudley and Tina Sharp Chair for Cancer Research at Baylor College of Medicine, Houston, was also impressed with the findings.

“The data look promising, and now that we can control the bone problems related to estrogen deprivation (with bisphosphonates), the use of aromatase inhibitors is more attractive. Although we don’t have a direct comparison with tamoxifen, now with longer-term data, for the very high–risk patient, I might use an aromatase inhibitor. If the patient cannot tolerate it, we can go back to tamoxifen,” he said.

Dr. Osborne acknowledged that not all healthy women will be willing to take an aromatase inhibitor. “It depends on who is talking to them,” he said. He pointed out that chemoprevention is not so much the purview of the oncologist as the gynecologist, and this specialty is often not fully informed on the topic.

“Prevention therapy is generally underutilized,” he said. “Gynecologists usually don’t know about it, or they are afraid to suggest it because they are afraid of endometrial cancer. In 40 years, I’ve seen only two cases [of endometrial cancer in the setting of prevention with tamoxifen], and it’s almost always curable.” 

DISCLOSURE: Dr. Patt has served in a leadership role for McKesson and Texas Oncology, Inc; has an immediate family member who has served in a leadership role for Mednax; has an immediate family member who owns stock or other ownership interests in Mednax; has received institutional research funding from Eisai, Lilly, Merck, and Seattle Genetics; and has been reimbursed for travel, accommodations, or other expenses by McKesson. Dr. Osborne has served on advisory boards or as a consultant for Genentech, AstraZeneca, and Tomar Pharma and holds stock in GeneTex.

REFERENCES

1. Goss PE, Ingle JN, Alés-Martínez J, et al: Exemestane for breast-cancer prevention in postmenopausal women. N Engl J Med 364:2381-2391, 2011.

2. Cuzick J, Sestak I, Forbes JF, et al: First results of the international breast cancer prevention study II (IBIS-II). 2019 San Antonio Breast Cancer Symposium. Abstract S3-01. Presented December 12, 2019.