Estimating the incidence of breast cancer recurrence using administrative data

Proton Reirradiation for High-Risk Recurrent or New Primary Breast Cancer

Radiotherapy is an integral component of multidisciplinary breast cancer care. Given how commonly radiotherapy is used in the treatment of breast cancer, many patients with recurrences have received previous radiotherapy. Patients with new primary breast cancer may also have received previous radiotherapy to the thoracic region. Curative doses and comprehensive field photon reirradiation (reRT) have often been avoided in these patients due to concerns for severe toxicities to organs-at-risk (OARs), such as the heart, lungs, brachial plexus, and soft tissue. However, many patients may benefit from definitive-intent reRT, such as patients with high-risk disease features such as lymph node involvement and dermal/epidermal invasion. Proton therapy is a potentially advantageous treatment option for delivery of reRT due to its lack of exit dose and greater conformality that allow for enhanced non-target tissue sparing of previously irradiated tissues. In this review, we discuss the clinical applications of proton therapy for patients with breast cancer requiring reRT, the currently available literature and how it compares to historical photon reRT outcomes, treatment planning considerations, and questions in this area warranting further study. Given the dosimetric advantages of protons and the data reported to date, proton therapy is a promising option for patients who would benefit from the added locoregional disease control provided by reRT for recurrent or new primary breast cancer.

Safety of Vaginal Estrogen Therapy for Genitourinary Syndrome of Menopause in Women With a History of Breast Cancer

OBJECTIVE

To assess the risk of recurrence of breast cancer associated with vaginal estrogen therapy in women diagnosed with genitourinary syndrome of menopause with a history of breast cancer using a large U.S. claims database.

METHODS

A U.S. health research network (TriNetX Diamond Network) was queried from January 2009 to June 2022. Our cohort consisted of women diagnosed with breast cancer within 5 years before the initial genitourinary syndrome of menopause diagnosis. Patients with active disease , defined as those undergoing mastectomy, radiation treatment, or chemotherapy within 3 months before diagnosis of genitourinary syndrome of menopause, were excluded. Recurrence was defined as mastectomy, radiation, chemotherapy, or secondary malignancy within 3 months to 5 years after the initiation of vaginal estrogen therapy for genitourinary syndrome of menopause. The study cohort included those with three or more vaginal estrogen prescriptions. The control cohort included women with breast cancer without any vaginal estrogen prescriptions after genitourinary syndrome of menopause diagnosis. Propensity matching was performed. A subanalysis by positive estrogen receptor status, when available, was performed.

RESULTS

We identified 42,113 women with a diagnosis of genitourinary syndrome of menopause after breast cancer diagnosis with any estrogen receptor status, 5.0% of whom received vaginal estrogen. Of the initial cohort, 10,584 patients had a history of positive estrogen receptor breast cancer, and 3.9% of this group received vaginal estrogen. Risk of breast cancer recurrence was comparable between those who received vaginal estrogen and those who did not in both the any estrogen receptor (risk ratio 1.03, 95% CI 0.91-1.18) and positive estrogen receptor (risk ratio 0.94, 95% CI 0.77-1.15) status analyses.

CONCLUSION

In a large, claims-based analysis, we did not find an increased risk of breast cancer recurrence within 5 years in women with a personal history of breast cancer who were using vaginal estrogen for genitourinary syndrome of menopause.