ImportanceCancer imposes a substantial economic burden on patients that may be worse in patients with higher-stage disease due to the need for more therapy.ObjectiveTo investigate the out-of-pocket costs (OOPCs) attributable to the initial treatment of common cancers among privately insured individuals diagnosed at different stages.Design, Setting, and ParticipantsThis retrospective cohort study used administrative claims data of a large national insurer in the US linked to the Surveillance, Epidemiology, and End Results (SEER) cancer registry to compare OOPCs of individuals diagnosed with breast, colorectal, and lung cancer at different stages with OOPCs of similar individuals without cancer using difference-in-differences methods. Individuals living in the US between 2008 and 2022, aged younger than 65 years, insured through a large national private health insurer, and with 6 or more months of continuous enrollment were included. Data were analyzed from June 2024 through February 2025.ExposureThe presence or absence of an incident cancer diagnosis and disease stage from the SEER registry diagnosed from 2008 to 2019.Main Outcomes and MeasuresThe primary outcome was OOPCs among individuals with breast, colorectal, and lung cancer diagnosed at different disease stages compared with those with no cancer diagnosis.ResultsThe cohort consisted of 46 158 patients (mean [SD] age at diagnosis, 46 [12] years; 30 733 female [66.6%]; 2543 Asian [5.5%], 4114 Black [8.9%], 3590 Hispanic [7.8%], and 31 099 White [67.4%]), including 19 656 patients with cancer and 26 502 patients without cancer in the control group. Among patients with cancer, 14 581 patients had breast cancer, 2842 patients had colorectal cancer, and 2233 patients had lung cancer. An incident cancer diagnosis was associated with a mean increase in OOPCs of $592.53 per month (95% CI, $528.01-$627.04 per month) for the 6 months after the diagnosis. Cost monotonically increased with stage at diagnosis (mean OOPC increase range, $462.01 per month [95% CI, $417.92-$506.11 per month] for stage 0 to $719.97 per month [95% CI, $626.11-$813.83 per month] for stage 4).Conclusions and RelevanceIn this study of individuals with private insurance, patients faced high OOPCs after an incident diagnosis of cancer, with patients with more advanced cancer having the highest OOPCs. Further research is needed to determine the clinical and financial effects of increased OOPCs for patients with cancer.
Transitions Within and Use of Outpatient Primary and Oncology Care in Survivors of Adolescent and Young Adult-Onset Cancers
JCO Oncology Practice | June 20, 2025 | Volume: 22 | Issue: 5 | Pages: 780-792
PURPOSE Survivors of adolescent and young adult (AYA)-onset cancers require comprehensive cancer surveillance care. Guidelines recommend 1-4 clinician visits annually for 5 years depending on stage and disease. The goal of this study was to identify factors associated with patterns of post-treatment primary and oncology care in a large cohort of survivors of AYA-onset cancers diagnosed within an integrated health care system. METHODS Patients diagnosed with cancer between 2006 and 2020 age 15-39 years were included. Surveillance visits were identified from electronic medical records 2-5 years after diagnosis. Multivariable logistic regression was used to assess associations with zero oncology specialty visits. RESULTS Of 7,925 survivors, 46% were Hispanic, 6% non-Hispanic Black, 11% non-Hispanic Asian, 35% non-Hispanic White, and 65% female. One-quarter had no oncology specialty visits in the first surveillance year rising to 38% in year 5; 31% had 3+ visits in the first year, declining to 13% in year 5. Over the surveillance period, 17% did not have any oncology specialty visits and 6% had no primary care or oncology visits. Those who were male (odds ratio [OR], 1.21 [95% CI, 1.02 to 1.45]), 20-24 years at diagnosis (OR, 1.58, 95% CI, 1.27 to 1.9; v 35 to 39), or non-Hispanic Black (OR, 1.38, 95% CI, 1.05 to 1.82; v non-Hispanic White) or had high-deductible commercial or Medicaid insurance (OR, 1.35, 95% CI, 1.15 to 1.59; OR, 1.42, 95% CI, 1.11 to 1.82, respectively; v no or low deductible commercial) were more likely to be in the 0-visit group for oncology specialty care. CONCLUSION Although the majority of this cohort received either primary or oncology specialty care, our study identifies those who may need tailored outreach for follow-up care. Continued research into development and testing of interventions to improve uptake of appropriate health care for survivors of AYA-onset cancers is critical.
Using Electronic Health Records to Classify Cancer Site and Metastasis
AbstractThe Enhanced EHR-facilitated Cancer Symptom Control (E2C2) Trial is a pragmatic trial testing a collaborative care approach for managing common cancer symptoms. There were challenges in identifying cancer site and metastatic status.This study compares three different approaches to determine cancer site and six strategies for identifying the presence of metastasis using EHR and cancer registry data.The E2C2 cohort included 50,559 patients seen in the medical oncology clinics of a large health system. SPPADE symptoms were assessed with 0 to 10 numeric rating scales (NRS). A multistep process was used to develop three approaches for representing cancer site: the single most prevalent International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) code, the two most prevalent codes, and any diagnostic code. Six approaches for identifying metastatic disease were compared: ICD-10 codes, natural language processing (NLP), cancer registry, medications typically prescribed for incurable disease, treatment plan, and evaluation for phase 1 trials.The approach counting the two most prevalent ICD-10 cancer site diagnoses per patient detected a median of 92% of the cases identified by counting all cancer site diagnoses, whereas the approach counting only the single most prevalent cancer site diagnosis identified a median of 65%. However, agreement among the three approaches was very good (kappa > 0.80) for most cancer sites. ICD and NLP methods could be applied to the entire cohort and had the highest agreement (kappa = 0.53) for identifying metastasis. Cancer registry data was available for less than half of the patients.Identification of cancer site and metastatic disease using EHR data was feasible in this large and diverse cohort of patients with common cancer symptoms. The methods were pragmatic and may be acceptable for covariates, but likely require refinement for key dependent and independent variables.
Clinical effectiveness of best-evidence cancer distress management in a real-world practice setting
Translational Behavioral Medicine | June 4, 2025 | Volume: 15 | Issue: 1 | Pages: No page available
Abstract Background Despite 40 years of evidence supporting psychosocial interventions as a component of comprehensive cancer care, patients continue to report vast unmet psychosocial needs and distress. Cognitive behavioral therapies for cancer distress (CBT-C) are the most rigorously tested class of psychosocial interventions for cancer care. Purpose To report clinical effectiveness outcomes of cancer-related distress and self-efficacy following implementation of best-evidence CBT-C, adapted for a real-world, billable practice setting. Methods Patients who completed group-delivered, CBT-C (10 intervention hours, 5 sessions) in the practice setting were invited to enroll in a research study to document cancer distress across the year following CBT-C. Participants (n = 65) were primarily middle-aged (mean 50.5 years, 17% were young adults ≤40 years), female, and White. Analyses utilized mixed linear models with intent-to-treat procedures. Given group delivery and social skills training content within CBT-C, social self-efficacy was assessed as a potential treatment mechanism. Results Distress decreased across the year following CBT-C (mean score change of 20 points for YAs, 6 points for non-YAs), with statistically significant age x time effects. Within-person improvements in social self-efficacy scores were related to reductions in cancer distress, including distress subscales of intrusive thoughts, avoidant coping, and hyperarousal. The model explained 76.6% of the total variance in cancer distress. Conclusions This study demonstrates the effective translation of CBT-C from controlled research trials to the practice setting. CBT-C effectiveness within a mixed-cancer population and relatively rural region of the US is also supported. CBT-C can be effectively translated to the practice settings for which it is intended.
Understanding patient preferences for supplemental methods of communication of new drug approvals in breast cancer survivors.
Journal of Clinical Oncology | May 28, 2025 | Volume: 43 | Issue: 16_suppl | Pages: No page available
e13551 Background: The landscape of cancer care is evolving rapidly. In 2023, there were 83 new FDA oncology approvals, and 145 interventional treatment (tx) studies opened across Mayo Clinic. We are exploring novel precision outreach approaches utilizing an LLM-integrated chatbot application to “ping” patients (pts) with specific clinical or genomic characteristics about newly available drugs or clinical trials. As novel outreach methods are considered, we surveyed a patient (pt) support group to understand communication preferences and awareness of adjuvant CDK4/6 inhibitors in tx of breast cancer (BC). Methods: On October 7, 2024, we administered a cross-sectional survey to 41 members of the Breast Cancer Support Network (BCSN) in Rochester, MN as a part of an IRB exempt quality improvement project. Leaders of the BCSN shared information to all participants, noting that the survey’s intent was to represent the pt voice and participation was voluntary. Anonymous survey data were collected with descriptive results reported. Results: 34/41 participants in the BCSN shared demographic information. The majority (83%) were > 50 years of age. 47% reported stage I BC, 12% stage II, 6% stage III, and 35% were unsure of their stage. Most participants (26/34, 76%) reported that their BC was hormone receptor positive (HR+), 2 HER-2 positive, and 6 unsure of their BC receptor status. 24/26 (92%) of pts with HR+ BC were taking or planning to start adjuvant endocrine therapy. 10/34 (29%) were aware that adjuvant CDK 4/6 inhibitors were approved. Of these 10 participants, 2 learned of it from online health resources, 6 from their clinician, 1 from social media, and 1 from a support group. The majority (66%) were unsure if they qualified for these drugs. Regarding receipt of information on new drug approvals/tx options, the highest ranked communication preference was to receive this information in person at an upcoming visit (ranked 1st by 50% of participants), followed by EHR-based message (28%), email (10%), phone call (6%), letter (4%), or an interactive chatbot (0%). Most respondents noted that communication from their healthcare provider was very important (30/37, 81%), with others stating that this was somewhat important (5/37, 14%) or neutral (2/37, 5%). Most noted that receiving information about tx options via video or visual aid before a visit would be very helpful (33/41, 80%). When asked about follow up after learning of a new drug approval, 17/32 (53%) of pts preferred an appointment, 9/32 (28%) a phone call, 3/32 (9%) a decision aid tool, and 3/32 (9%) a questionnaire to assess their understanding. Conclusions: Providing personalized, timely communication about new FDA approved tx options is important for BC survivors and critical for improving care delivery. While technological solutions could broaden awareness, this requires balancing pt preferences for direct communication with clinicians.
Estrogen receptor expression in residual breast cancer following neoadjuvant chemotherapy.
Journal of Clinical Oncology | May 28, 2025 | Volume: 43 | Issue: 16_suppl | Pages: 529-529
529 Background: Neoadjuvant chemotherapy (NAC) is commonly administered to patients (pts) with estrogen receptor alpha (ER) negative (immunohistochemistry [IHC] 0%) and ER-low (IHC 1-10%) breast cancer (BC). For pts without pathological complete response (pCR), ER expression may differ between baseline and residual BC following NAC. We previously demonstrated adjuvant endocrine therapy (ET) omission in ER-low early-stage BC was associated with significantly worse overall survival (OS); however, this effect was restricted to pts with residual BC following NAC and those with higher baseline ER levels (IHC 6-10%) (Choong et al., ASCO 2024). Here, we assessed how often ER was expressed in residual invasive BC for pts treated with NAC for ER-negative and ER-low BC. Methods: Weidentified pts with pre-treatment (tx) ER-negative and ER-low (regardless of HER2 expression) stage I-III BC treated with NAC who underwent BC surgery at Mayo Clinic Rochester between 2009 and 2023. ER IHC was performed in a CAP/CLIA laboratory. We evaluated ER expression in residual invasive BC for pts without pCR. The percent of pts with a post-tx change in ER status was estimated and reported with 95% Wilson confidence intervals. Results: 955 pts (838 [88%] pre-tx ER-negative; 117 [12%] pre-tx ER-low) met inclusion criteria, of whom 69% had HER2-negative and 31% HER2-positive BC. The median age at diagnosis was 52 (range: 24-86). 496 (52%) had residual BC. Residual BC was more common in HER2-negative versus (vs) positive tumors (56% vs 42%, p < 0.001) but did not differ significantly by ER status (ER-negative 51% vs ER-low 57%, p = 0.22). Of those with residual BC, 277/496 (56%) had ER re-testing. Rates of ER re-testing did not vary for pre-tx ER-negative vs -low (57% vs 51%, p = 0.37) but were significantly lower for HER2-positive vs HER2-negative tumors (39% vs 62%, p < 0.001). Among those with post-tx testing, 31/277 (11%, 95% CI: 8-15%) had an increase in ER expression from pretreatment levels (defined as ER IHC < 1% to either 1-10% or > 10%; or ER IHC 1-10% to > 10%). In these 31 pts, the original NAC was for either TNBC (21/31; 68%) or HER2+ BC (10/31; 32%). In pts with pre-tx ER-negative BC, 27/243 (11%, 95% CI: 8-16%) had ER expression in the residual BC including 14/243 (6%, 95% CI: 3-9%) with ER > 10% and 13/243 (5%, 95% CI: 3-9%) with ER 1-10%. For pts with baseline ER-low BC, 4/34 (12%, 95% CI: 5-27%) had ER > 10% in the residual BC. Among the 31 pts where ER increased following NAC, 21/31 (68%) received adjuvant ET, including 17/18 if ER was > 10% in the residual disease and 4/13 in those with ER 1-10%. Conclusions: In pts treated with NAC for ER-negative or ER-low BC not achieving pCR, we identified higher ER expression in the residual breast cancer in > 10% of pts. Given that omission of ET in ER-low BC with residual cancer following NAC is associated with worse survival, repeat biomarker testing should be considered in those without pCR, and ET individualized according to ER expression.
Impact of a collaborative care-based symptom intervention model on chemotherapy adherence in patients with breast cancer.
Journal of Clinical Oncology | May 28, 2025 | Volume: 43 | Issue: 16_suppl | Pages: 1543-1543
1543 Background: Treatment toxicity may limit the ability of cancer patients to receive all recommended cycles of therapy. Four to six cycles of docetaxel plus cyclophosphamide (TC) is a common adjuvant chemotherapy regimen for early-stage breast cancer. We assessed the impact of routine collection of patient-reported outcomes (PROs), coupled with a collaborative care model-based symptom management intervention, on the number of cycles of TC received by patients with breast cancer. Methods: The Enhanced, EHR-facilitated Cancer Symptom Control (E2C2) trial was a cluster-randomized, pragmatic clinical trial, conducted between March 2019 and January 2023 at Mayo Clinic Rochester and within the Mayo Clinic Health System in Minnesota and Wisconsin. Patients regularly reported the severity of 6 SPPADE symptoms (Sleep deficit, Pain, Physical function impairment, Anxiety, Depression, and Energy deficit/fatigue) on 11-point numerical rating scales. Each symptom score was interpreted as none to mild (0-3), moderate (4-6), or severe (7-10). The E2C2 intervention included symptom management education modules, clinician decision support aids, and the option to discuss severe symptoms with a nurse, physical therapist, or social worker. Patients with breast cancer who received at least one cycle of TC were included in this analysis. We compared the number of cycles of docetaxel and cyclophosphamide completed by patients in the control condition versus those in the intervention condition. Results: We identified 198 patients with breast cancer who received TC during the control condition and 128 who received TC during the intervention condition. Median age was 61.3 years in the control group and 60.3 years in the intervention group, and 94% and 95% were white, respectively. Those receiving treatment during the control condition, on average, completed 3.53 cycles of docetaxel, while those receiving TC during the intervention condition completed 3.77 cycles ( p = 0.014). Seventy-eight percent in the control group completed at least 4 cycles of docetaxel, compared to 84% in the intervention group. Those receiving TC during the control condition completed an average of 3.71 cycles of cyclophosphamide, compared to 3.78 cycles in the intervention condition (p = 0.231). Eighty-four percent of patients in the control group and 86% in the intervention group completed at least 4 cycles of cyclophosphamide. Conclusions: Routine PRO surveillance, coupled with guideline-based collaborative care interventions, was associated with completion of a greater number of cycles of docetaxel. These findings suggest that routine symptom surveillance and management may enhance the docetaxel tolerance profile and improve treatment adherence in patients with early-stage breast cancer, allowing for delivery of an optimized treatment course.
MHC class I expression and outcomes in breast cancer in the real-world clinico-genomic data and the FinXX trial.
Journal of Clinical Oncology | May 28, 2025 | Volume: 43 | Issue: 16_suppl | Pages: 570-570
570 Background: Major histocompatibility complex class I (MHC I) plays a critical role in immune surveillance by binding peptides derived from intracellular proteins and presenting them on the cell surface for recognition by CD8+ T cells. Loss or downregulation of MHC I expression has been identified as a key mechanism of immune evasion in cancers. Here, we evaluated MHC I expression and outcomes in all subtypes of breast cancer (BC). Methods: 9,038 BC samples were analyzed via NGS (592-gene panel, NextSeq; WES/WTS, NovaSeq; Caris Life Sciences, Phoenix, AZ), including triple-negative BC (TNBC) 3,038, HER2-positive (HER2+) 1,082, and hormone receptor-positive (HR+HER2-) 4,918. Immune cell fractions were estimated using WTS deconvolution (Quantiseq). MHC I ( HLA-A / HLA-B / HLA-C )-high (H) and -low (L) were classified by RNA expression above or below the 25th percentile. Real-world overall survival (OS) was derived from insurance claims and calculated from tissue collection to last contact using Kaplan-Meier. NanoString IO360 was performed in 114 samples from the FinXX trial (NCT00114816). Statistical significance was assessed using chi-square, Mann-Whitney U, ANOVA, and Cox regression with multiple comparison adjustments (q<.05). Results: TNBC had higher expression of HLA-A and HLA-B (median TPM: 169 and 191) compared to HER2+ (146.6 and 170, q<0.05) and HR+HER2- (141.7 and 157.5, q<0.05). However, there was no significant difference in HLA-C expression across 3 BC subtypes. In TNBC, MHC I-H tumors had higher frequencies of PD-L1 positivity (66.2% vs. 13.1%) as well as higher infiltration of B cells (4.5% vs. 3.2%), M1 macrophages (5% vs. 1.5%), M2 macrophages (4% vs. 2.1%), Tregs (2.8% vs. 0.8%), CD8 + T cells (1.8% vs. 0%), dendritic cells (3.2% vs. 2.8%), higher T-cell inflamed score (137 vs. -144), and IFN g score (0.02 vs. -0.49) compared to MHC I-L TNBC (all q<.05). MHC I-H TNBC was associated with significant improvement in median OS (30.1 vs. 15.2 months, HR 0.55, 95% CI 0.46-0.65, p<0.0001). However, this survival difference was not observed in patients with MHC I-H vs. MHC I-L in HER2+ (HR 1.04, 95% CI 0.74-1.47, p = 0.81) and HR+HER2- (HR 0.87, 95% CI 0.75-1.02, p= 0.09) BC subtypes. We further validated the MHC I expression in the FinXX trial. Similarly, patients with MHC I-H had significant improvement in recurrence-free survival (HR 0.27, 95%CI 0.11-0.66, p = 0.002) and OS (HR 0.23, 95% CI 0.09-0.57, p = 0.0005) compared to MHC I-L. Conclusions: Our findings demonstrate that higher MHC I expression is associated with higher immune infiltration and improved outcomes in TNBC but not in HER2+ or HR+HER2- BC subtypes. These results suggest that MHC I expression plays a critical role in the tumor microenvironment of TNBC. Future studies are needed to evaluate the prognostic value and potential therapeutic target of MHC I in TNBC. Support: Breast Cancer Research Foundation, Bankhead Coley, W81XWH-18-1-0564. Clinical trial information: NCT00114816 .
Early adverse symptoms to predict response to treatment among patients in the I-SPY trial.
Journal of Clinical Oncology | May 28, 2025 | Volume: 43 | Issue: 16_suppl | Pages: 610-610
610 Background: The adverse event (AE) landscape in oncology is changing due to the introduction of immunotherapy and antibody drug conjugates. These AEs come with both short and long-term symptoms that significantly impact patient quality of life. Monitoring for early onset of symptoms could optimize therapy for a particular patient, maximizing potential efficacy while mitigating toxicity. It is also possible that some toxicities are directly associated with drug sensitivity. We sought to identify symptoms associated with pathologic complete response (pCR) using patient-reported outcomes (PROs) in early-stage high-risk breast cancer patients. Methods: Our study population included 288 stage II/III high-risk breast cancer patients enrolled on the I-SPY2 trial from 2021-2024, who received novel neoadjuvant therapies ± standard paclitaxel. pCR was assigned if tumor was absent in breast and nodes at surgery following neoadjuvant treatment. Patients (n = 288, pCR rate = 29%, 89% administered immunotherapy) were sent electronic PROs. 33 patient-reported AEs were measured using NCI's Patient Reported Outcomes - Common Terminology Criteria for Adverse Events (PRO-CTCAE). Each symptom was evaluated using severity, frequency, and interference on a Likert Scale. Presence of early PRO symptoms (cycles 1-3 of treatment) were binarized (at least one of moderate or greater), and odds ratios were computed with pCR as outcome. To assess whether higher grade AEs were enriched in patients that achieved a pCR, we also performed the Wilcoxan rank sum test using maximum (worst) symptom severity. Results: Of 288 patients included in our analysis (median age = 48 years, range = 20-78), 203 (70.5%) were White, 17 (5.9%) were Asian, 33 (11.5%) were Black or African American, and 35 (12.2%) were Hispanic. PRO analysis revealed that patients that had moderate to severe muscle pain (27% vs 10% OR = 3.15, p < 0.05), joint pain (22% vs 8% OR = 3.23, p < 0.05), headache (27% vs 12.5% OR = 2.59, p < 0.05), or mouth/throat sores (16% vs 5% OR = 3.56, p < 0.05) within weeks 1-3 had higher odds of achieving a pCR. When we looked at maximum severity between weeks 1-3, patients that achieved a PCR had higher grade muscle pain (p = 0.04), heart palpitations (p = 0.035), and significantly lower grade numbness and tingling (p = 0.002). Beyond 6 weeks, associations were weaker or insignificant. Conclusions: Our study utilizes an analysis framework that was able to determine sentinel symptoms such as muscle and joint pain, mouth/throat sores and palpitations as early as weeks 1-3 associated with increased efficacy. This may suggest an early immune reaction in patients that eventually respond favorably to treatment. Our work can help provide earlier proactive monitoring to mitigate toxicities, treatment redirection if needed, and a potential symptom-based early understanding to personalize treatment efficacy. A similar analysis is underway to predict immune related AEs. Clinical trial information: NCT01042379 .
Impact of pregnancy history and recency of childbirth on long-term outcomes in young patients with early-stage breast cancer.
Journal of Clinical Oncology | May 28, 2025 | Volume: 43 | Issue: 16_suppl | Pages: No page available
e12562 Background: Previous research has suggested that breast cancer (BC) diagnosed during pregnancy or the postpartum period exhibits more aggressive clinical features, possibly due to pregnancy-related hormonal changes, immune modulation, and alterations in the mammary microenvironment compared to nulligravid or women many years out from pregnancy. Emerging data have demonstrated potential worse outcomes for patients (pts) diagnosed in post-partum. This study evaluated the influence of timing of diagnosis in relation to pregnancy history and recency of childbirth on long-term outcomes in a modern cohort of young pts with early-stage BC. Methods: Pts with stage I–III BC age < 40y in the prospective Young Women’s Breast Cancer Study (YWBCS) were categorized at diagnosis as Nulligravid (no prior pregnancy), Nulliparous (prior pregnancy without live birth), Currently Pregnant, or Parous (subdivided by time since last childbirth: within 5 years [≤ 5y PP], and 5–10 years postpartum [5–10y PP]). Baseline characteristics and outcomes were compared across BC subtypes (estrogen receptor+/HER2- [ER+/HER2-], HER2+, and triple-negative BC [TNBC]). Prognostic analyses for distant recurrence-free survival (DRFS) used Cox models. Results: 859 pts were included, 257 (30%) nulligravid, 50 (6%) nulliparous, 37 (4%) pregnant, and 515 (60%) parous (348 [68%] were ≤5y PP, and 167 [32%] were 5–10y PP). Median follow-up was 133 (6–209) months. Median age at diagnosis was lower in nulligravid pts (33 vs. 35–38 years); T1 tumors were most common in pts >5y PP (62%), and N0 status was highest in nulligravid pts (64%) (all p < 0.0001). Pregnant pts had higher rates of TNBC (27%), and T3 tumors (14%), N1 status, N1 (41%), and Grade 3 (81%) tumors compared to other groups (all p < 0.0001). Overall, only tumor size (T2-T4 vs T1, HR 2.03; 95% CI 1.37–3.03) and nodal status (N1 vs N0, HR 2.22; 1.48–3.34; N2/3 vs N0, HR 3.23; 1.96-5.33) were independently associated with worse DRFS; pregnancy history was not: nulligravid + nulliparous pts had no significant differences in DRFS compared to Pregnant (HR 1.46; 0.75–2.86), Parous <5y PP (HR 0.86; 0.58–1.26), and Parous 5–10y PP (HR 0.89; 0.54–1.48). Subgroup analyses by BC subtype (Table) and sensitivity analyses (excluding currently pregnant pts or separating nulligravid and nulliparous pts) demonstrated no significant associations between pregnancy history and DRFS. Conclusions: In this cohort study of very young patients with early breast cancer with contemporary treatment including management of breast cancer during pregnancy, pregnancy history and recency of pregnancy were not independent predictors of long-term disease outcomes. DRFS results by subgroup. Pregnancy Group N (%) HR (95% CI) ER+/HER2- Nulligravid + Nulliparous 173 (38.1) Ref Pregnant 16 (3.5) 0.93 (0.32–2.70) Parous ≤5y PP 177 (39.0) 0.77 (0.45–1.29) Parous 5–10y PP 88 (19.4) 0.78 (0.39–1.53) HER2+ Nulligravid + Nulliparous 77 (30.8) Ref Pregnant 11 (4.4) 3.27 (0.80–13.38) Parous ≤5y PP 113 (45.2) 1.50 (0.60–3.75) Parous 5–10y PP 49 (19.6) 1.45 (0.45–4.66) TNBC Nulligravid + Nulliparous 56 (36.8) Ref Pregnant 10 (6.6) 1.92 (0.61–6.09) Parous ≤5y PP 57 (37.5) 0.68 (0.28–1.63) Parous 5–10y PP 29 (19.1) 1.16 (0.43–3.14)