Key Points Question Is there an increased risk for metastasis of breast cancers that are diagnosed in young women post partum that extends beyond 5 years from the last childbirth, and what association do standard clinical prognostic factors have with metastatic risk in these young women when categorized by parity? Findings In a cohort study of 701 women 45 years or younger with breast cancer, those with stage I or II cancer diagnosed up to 10 years post partum had an increased risk for distant metastasis, with both estrogen receptor–positive and estrogen receptor–negative disease significantly affected. Meaning Postpartum status may be a prognostic indicator in young women with breast cancer and should be routinely identified, as up to 45% of women 45 years or younger with breast cancer fall into this category and could be at increased risk for metastasis.

ImportanceBreast cancer diagnosed within 5 to 10 years after childbirth, called postpartum breast cancer (PPBC), is associated with increased risk for metastasis and death. Whether a postpartum diagnosis is an independent risk factor or a surrogate marker of cancer features associated with poor outcomes remains understudied.ObjectiveTo determine whether diagnostic temporal proximity to childbirth is associated with features of breast cancer associated with poor outcomes, including tumor stage, estrogen receptor (ER) status, and risk for distant metastasis and breast cancer–specific mortality, using a population database from the state of Utah.Design, Setting, and ParticipantsThis population-based cohort study using the Utah Population Database (UPDB) included individuals with stage I to III breast cancer diagnosed at age 45 years or younger between 1996 and 2017, followed-up until February 2020. Participant data were analyzed from November 2019 to August 2022.ExposureThe primary exposures were no prior childbirth or time between most recent childbirth and breast cancer diagnosis. Patients were grouped by diagnoses within less than 5 years, 5 to less than 10 years, or 10 years or more since recent childbirth.Main Outcomes and MeasuresThe 2 primary outcomes were distant metastasis–free survival and breast cancer–specific death. Cox proportional hazard models were used to investigate associations between exposures and outcomes adjusting for diagnosis year, patient age, tumor stage, and estrogen receptor (ER) status.ResultsOf 2970 individuals with breast cancer diagnosed at age 45 years or younger (mean [SD] age, 39.3 [5.0] years; 12 Black individuals [0.4%], 2679 White individuals [90.2%]), breast cancer diagnosis within 5 years of recent childbirth was independently associated with approximately 1.5-fold elevated risk for metastasis (hazard ratio [HR], 1.5; 95% CI, 1.2-2.0) and breast cancer–specific death (HR, 1.5; 95% CI, 1.1-2.1) compared with nulliparous individuals. For cancers classically considered to have tumor features associated with good outcomes (ie, stage I or II and ER-positive), a postpartum diagnosis was a dominant feature associated with increased risk for metastasis and death (eg, for individuals with ER-positive disease diagnosed within <5 years of childbirth: age-adjusted metastasis HR, 1.5; 95% CI, 1.1-2.1; P = .01; age-adjusted death HR, 1.5; 95% CI, 1.0-2.1; P = .04) compared with nulliparous individuals. Furthermore, liver metastases were specifically increased in the group with diagnosis within 5 years postpartum and with positive ER expression (38 of 83 patients [45.8%]) compared with the nulliparous (28 of 77 patients [36.4%]), although the difference was not statistically significant. Overall, these data implicate parity-associated breast and liver biology in the observed poor outcomes of PPBC.Conclusions and RelevanceIn this cohort study of individuals with breast cancer diagnosed at age 45 years or younger, a postpartum breast cancer diagnosis was a risk factor associated with poor outcomes. Irrespective of ER status, clinical consideration of time between most recent childbirth and breast cancer diagnosis could increase accuracy of prognosis in patients with young-onset breast cancer.

Objectives: The anti-CTLA-4 and antiprogrammed cell death-1 (PD-1) therapies have significantly improved survival of patients with metastatic melanoma. However, there is limited data regarding the interaction between immunotherapy (IT) and stereotactic radiosurgery (SRS) in patients with brain metastasis, particularly how combination therapy may affect toxicity and intracranial tumor control. Methods: We retrospectively reviewed 26 patients with metastatic melanoma who received immune check point inhibitors and SRS for brain metastasis from 2011 to 2017. We evaluated lesions receiving SRS concurrently (within 30 days) and sequentially with IT. Overall survival (OS), local control (LC), and regional progression free survival (RPFS) were determined. Results: In total, 26 patients and 90 lesions were treated using pembrolizumab, nivolumab and/or ipilimumab, sequentially, or concurrently with SRS. Median follow-up was 18.9 months (range, 4.9 to 62.3 mo). Median overall survival was 26.1 months. There were 3 local failures, but no significant difference between the 2 groups. Following concurrent SRS and immunotherapy, patients had a significantly longer period of intracranial progression free survival than those treated with nonconcurrent therapy, 19 months versus 3.4 months (P<0.0001). No grade 4-5 toxicities were observed. Conclusions: Patients with melanoma metastatic to brain treated with SRS and immune checkpoint inhibitors had favorable median survival of 26.1 months compared with historical controls. Patients receiving immunotherapy within 30 days of SRS had significantly improved regional intracranial progression free survival compared with patients receiving sequential therapy. Our findings suggest synergy between checkpoint inhibitor immunotherapy and radiosurgery. Further studies are needed to confirm these findings.

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