Partridge, Ann H.

591 Background: Both Cb and Bev demonstrate activity when combined with standard chemotherapy in TNBC. CALGB 40603 is a 2x2 randomized trial that previously demonstrated that adding Cb to NACT significantly increased pathologic complete responses in the breast/axilla (pCR), while adding Bev did not (Sikov, JCO 2015). Here we report 5-year LTOs and assess factors that influenced them. Methods: 443 patients with clinical stage II-III previously untreated TNBC received 12 weeks of paclitaxel (wP) +/- Cb then dose-dense AC, +/- Bev before surgery. The primary endpoint was pCR. Analyses of LTOs (event-free survival (EFS), distant recurrence-free interval (DRFI) and overall survival (OS)), impact of residual cancer burden and other variables were secondary. Results: Median follow-up was 5.7 years (y); 5y EFS was 70.9% (95% CI; 66.7%-75.4%), DRFI 76.3% (72.3%-80.5%) and OS 76.9% (72.9%-81.2%). Pretreatment clinical stage and achieving pCR correlated with LTOs, while age, race, subtype (basal-like vs. not) and tumor grade did not. Among pCR 5y EFS was 86.4% vs. 57.5% for non-pCR (HR 0.28, 0.19-0.43), OS was 88.7% vs 66.5% (HR = 0.28, 0.17-0.44). This relationship was similar in all trial arms. Any residual disease conferred poorer outcome; compared with pCR/Residual Cancer Burden (RCB) 0, EFS HRs were 2.29 (1.32-3.97), 3.01 (1.90-4.74), and 9.67 (5.66-16.51) for RCBI, II and III, respectively. There were no improvements in LTOs with Cb (EFS HR 0.99, 0.70-1.40) or Bev (EFS HR 0.91, 0.64-1.29). In an exploratory analysis, receipt of ≥11 doses of wP was associated with better EFS (HR 1.92, 1.33-2.77); this was particularly notable in Cb-treated arms. Conclusions: As expected, regardless of treatment arm pCR was associated with markedly better LTOs, and pts with any residual disease had significantly worse outcomes. The addition of Cb or Bev to standard NACT for TNBC did not improve LTOs in this trial, although it should be noted that the trial was not powered for this endpoint. Omission of chemotherapy doses may result in poorer outcomes, especially among Cb-treated pts, which may warrant further evaluation. Support: U10CA180821; U10CA180882; Genentech; https://acknowledgments.alliancefound.org ; NCT00861705 Clinical trial information: NCT00861705.

554 Background: HER2+ breast cancer (BC) is particularly common in young women. Genomic features of HER2+ tumors before and after H-based therapy have not been described in a population of young women and may point to clinically targetable mechanisms of resistance. Methods: From a large prospective cohort of women diagnosed with BC age ≤40 years, we identified those with HER2+ BC and tumor tissue available for sequencing before and after chemo+H. Whole exome sequencing (WES) was performed on each tumor and on germline DNA from blood. Tumor-normal pairs were analyzed for mutations and copy number (CN) changes. Evolutionary analysis was performed for patients with both pre- and post-treatment (tx) samples. Results: 22 women had successful WES samples from at least one timepoint; 13 of these had paired sequencing results both before and after chemo+H. For the majority of women, post-tx sample was following neoadjuvant chemo + H, though post-tx timepoint for other women represented locoregional or distant metastasis (Table). TP53 was the only gene that was significantly recurrently mutated in both pre- and post-tx samples. Comparison of matched pre-tx and post-tx samples demonstrated that large changes in HER2 CN over the course of tx were uncommon, only 2/13 pts had > 2-fold change in HER2 CN. Other clonal and subclonal genomic alterations were found to be acquired in the post-tx sample compared to the pre-tx sample. One patient acquired a putative activating mutation in ERBB2. Another patient acquired a clonal hotpsot mutation in TP53. MYC gene amplification was observed in 4 post-tx tumors. NOTCH2 alterations were found in post-tx biopsies from 2 different patients, and mutations in STIL were also found in post-tx biopsies from 2 patients, though the function of these mutations is not known. Conclusions: HER2+ breast tumors in young women display genomic evolution following tx with chemo+H. HER2 CN changes are uncommon, but we identified several genes that warrant exploration as potential mechanisms of resistance to therapy in this population.[Table: see text]

Background Young age is a known factor associated with suboptimal adherence to endocrine therapy (ET) for adjuvant breast cancer (BC) treatment. This study was aimed at assessing nonadherent behaviors and associated factors among young women with early‐stage hormone receptor–positive BC. Methods As part of a multicenter, prospective cohort of women with a diagnosis of BC at or under the age of 40 years, participants were surveyed 30 months after their diagnosis about adherent behaviors. Among those who reported taking ET, adherence was measured with a 3‐item Likert‐type scale: Do you ever forget to take your ET? If you feel worse when you take your ET, do you stop taking it? Did you take your ET exactly as directed by your doctor over the last 3 months? Women reporting at least 1 nonadherent behavior were classified as nonadherers. Variables with a P value <.20 were included in a multivariable logistic model. Results Among 384 women, 194 (51%) were classified as nonadherers. Univariate factors that retained significance in the multivariable model included educational level (odds ratio [OR], 0.50 for high vs low; P = .04), level of social support according to the Medical Outcome Study Social Support Survey (OR, 0.98 per 1 point; P = .01), and confidence with the decision regarding ET measured on a 0 to 10 numerical scale (OR, 0.63 for high vs low; P = .04). Conclusions Findings from this study could help to identify young patients at higher risk for nonadherence. Interventions adapted to the level of education and aimed at reinforcing support and patients' confidence in their decision to take ET could improve adherence and associated outcomes in this population.

Abstract Background Young women are more likely than older women to present with higher stage breast cancer (BC) and may benefit to a greater extent from downstaging with neoadjuvant systemic treatment (NST). Young age is also associated with greater likelihood of pathologic complete response (pCR). Using a large prospective cohort of young women with BC, we investigated response to neoadjuvant therapy, eligibility for breast conserving surgery (BCS) pre- and post-NST, and surgical treatment. Methods The Young Women's Breast Cancer Study (YWS) is a multi-center cohort of women diagnosed with BC at age ≤40, that enrolled 1302 patients from 2006 to 2016. Disease characteristics and treatment information were obtained through medical record and central pathology review. Surgical recommendation before and after NST, conversion from BCS borderline/ineligible to BCS eligible, surgery, documented reasons for choosing mastectomy (MTX) among BCS eligible women, and final pathologic response were independently reviewed. Results Among 1302 women enrolled in YWS, 801 (62%) presented with unilateral stage I-III breast cancer and 317(40%) received NST. Median age was 36 years old (22-40). Pre-NST, 85/317 (27%) were BCS eligible, 49 (15%) were borderline, and 169 (53%) were not eligible (16 inflammatory breast cancer (IBC), 88 large tumor size /cosmetic, 48 diffuse calcifications, and 83 multicentricity). Among the 218 patients who were BCS ineligible/borderline pre-NST, 82 (38%) became eligible for BCS after NST. 4 patients who were BCS eligible pre-NST became ineligible. Of all patients eligible for BCS post-NST (n=163), 80 (49%) attempted BCS, 74 (93%) of whom were successful, and 83 (51%) chose MTX. Reasons for choosing MTX included: patient preference (38/83 (46%)), BRCA or TP53 mutation (31 (37%)), family history (3 (4%)), unknown (11 (13%)). On final pathology, 75 (24%) patients had pCR. Among patients who achieved a pCR, 48 (64%) underwent MTX, fewer than half (21/48 (44%)) were for anatomic indications (IBC, large tumor at diagnosis, diffuse calcifications, multicentric disease). Conclusion While NST doubled the proportion of young women eligible for BCS, nearly half chose MTX regardless of response to NST, mostly for personal preference or high-risk preventative reasons. These data highlight that surgical decision making among young women with breast cancer is often driven by factors beyond extent of disease and clinical response to therapy. Table 1.Clinical-pathologic characteristicsCharacteristicsNumber%Pre NST surgical recommendation BCS eligible8526.8Borderline4915.5BCS ineligible16953.3Unknown144.4Clinical Response Complete20263.7Partial9229.0Stable30.9Progressing72.2Unknown134.1Pathologic Response pCR (No invasive or DCIS)7524No pCR24276Post NST Surgical recommendation BCS eligible16351.4BCS ineligible14445.4Unknown103.2Attempted surgery BCS8025.2MTX23674.1Unknown20.6Final Surgery BCS7423.3MTX24176unknown20.6 Citation Format: Kim HJ, Dominici L, Rosenberg S, Pak LM, Poorvu PD, Ruddy K, Tamimi R, Schapira L, Come S, Peppercorn J, Borges V, Warner E, Vardeh H, Collins L, King T, Partridge A. Surgical treatment after neoadjuvant systemic therapy in young women with breast cancer: Results from a prospective cohort study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS6-01.

Abstract Background Less than 3% of older patients with cancer are enrolled in clinical trials. To reverse this underrepresentation, we compared older patients enrolled with older-patient-specific trials, defined as those designed for older patients with cancer, with those enrolled in age-unspecified trials. Materials and Methods We focused on individual patient data from those ≥65 years (younger patients excluded) and included all Alliance phase III adjuvant breast cancer trials from 1985–2012. Results Among 2,277 patients, 1,014 had been enrolled to older-patient-specific and 1,263 to age-unspecified trials. The median age (range) in the older-patient-specific trials was 72 (65–89) years compared with 68 (65–84) years in the cohort of older patients in age-unspecified trials; p &lt; .0001. A greater percentage of patients 75 years or older had enrolled in older-patient-specific trials compared with the cohort of age-unspecified trials: 26% versus 6% (p &lt; .0001). Median overall survival (OS) was 12.8 years (95% confidence interval [CI], 11.9–13.7) and 13.5 years (95% CI, 12.9–14.1) for older-patient-specific and age-unspecified trials, respectively. OS was comparable (hazard ratio [HR], 1.08; 95% CI, 0.92–1.28; p = .34; referent: age-unspecified trials), after adjusting for age, estrogen receptor status, tumor size, and lymph node status. Similar findings were reached for recurrence-free survival. A lower rate of grade 3–5 adverse events (hematologic and nonhematologic) was reported in older-patient-specific trials (43% vs. 58%; p &lt; .0001). Sensitivity analysis with chemotherapy only trials and subset analysis, adjusted for performance score, yielded similar OS results. Conclusion Older-patient-specific trials appear to address this underrepresentation of older patients with ostensibly comparable outcomes. Clinical trial identification numbers. NCT00003088 (CALGB 9741); NCT00024102 (CALGB 49907); NCT00068601 (CALGB 40401); NCT00005970 (NCCTG N9831)

AbstractObjectivesTo identify and characterize distinct trajectories of change in young women's sexual functioning over the first 5 years following breast cancer diagnosis.MethodsGroup‐based trajectory modeling was applied to the sexual functioning of 896 women diagnosed with stage I‐IV breast cancer at age 40 or younger. The Cancer Rehabilitation Evaluation System was used to evaluate women's symptoms of sexual dysfunction annually for 5 years.ResultsFive distinct trajectories of sexual functioning were identified: one asymptomatic, one minimally symptomatic, two moderately symptomatic, and one severely symptomatic trajectory. Twelve percent of women were asymptomatic throughout follow‐up. The plurality of women experienced stable mild symptoms (42%). Among those with moderate symptoms, some experienced improvement over time (22%) while others experienced deterioration (13%); 11% experienced stable severe symptoms that did not remit over time. Independent predictors of experiencing a symptomatic rather than asymptomatic trajectory (P < 0.05, two‐sided) included diagnosis with stage 2 versus 1 disease, ER positive disease treated with oophorectomy or ovarian suppression, being partnered, having anxiety, poorer body image, and greater musculoskeletal pain.ConclusionsWe identified distinct trajectories that describe the reported sexual symptoms in this cohort of young breast cancer survivors. The majority of women reported various degrees of sexual dysfunction that remained stable over the study period. There is, however, potential for improvement of moderate and severe symptoms of sexual dysfunction in early survivorship.