Peppercorn, Jeffrey

505 Background: Increased TILs are associated with better prognosis in triple-negative BC, including in patients (pts) age < 40. However, the role of TILs remains unclear in HR+/HER2- BC and little data exist in young pts, in whom immune microenvironment could be altered by age-related host/tumor differences. We assessed the extent and composition of immune infiltration in HR+ tumors of young women and correlated with clinicopathologic features and survival outcomes. Methods: From a prospective cohort study of women with BC diagnosed age ≤40, we identified those with stage I-III HR+/HER2- BC and available pre-treatment (tx) tumor tissue. Multiplexed immunofluorescence was used to quantify cytotoxic T (CD8+), T helper (Th, CD3+CD8-), T regulatory (Tregs, FOXP3+CD3+) and exhausted T (PD1+CD8+) cells in stroma and tumor. Univariate analyses tested associations between clinicopathologic variables and immune markers by high or low expression, divided based on median. High vs. low TILs were evaluated in Cox regression analyses for invasive breast cancer-free survival (iBCFS), distant disease-free survival (DDFS) and overall survival (OS). Results: In 390 pts, median age was 37 years (21-40), most had grade 2 (51%), T1 (65%), N0 (63%) tumors and 67% received adjuvant chemotherapy. Black pts (n = 17) had higher expression of stromal CD8+ ( P= .010), FOXP3+CD3+ ( P= .027) and PD1+CD8+ TILs ( P= .043); intratumoral TILs did not differ by race. Older age (36-40) was associated with high expression of CD8+ ( P= .033) and PD1+CD8+ TILs ( P= .031) within stroma and CD3+CD8- TILs within tumor ( P= .046). Grade 3 tumors had higher stromal and intratumoral expression of CD3+CD8- ( P= .002; P< .001) and FOXP3+CD3+ TILs ( P= .020; P< .001). No differences in TILs were seen according to recency of pregnancy, BRCA1/2 status or T/N stage. Over a median follow up of 8 years, 85 iBCFS events, 64 DDFS events and 37 deaths occurred. High stromal expression of CD3+CD8- TILs was associated with better iBCFS (HR 0.49, P= .002) and DDFS (HR 0.57, P= .046), which remained significant when adjusted for T/N stage, grade and chemotherapy (iBCFS HR 0.41, P< .001; DDFS HR 0.45, P= .008). High stromal expression of CD3+CD8- and FOXP3+CD3+ TILs was associated with better OS (HR 0.47, P= .038) and iBCFS (HR 0.58, P= .018), respectively, on adjusted analyses only. High intratumoral expression of CD3+CD8- and FOXP3+CD3+ TILs was associated with better iBCFS (HR 0.59, P= .025; HR 0.63, P= .043) after adjustment only. Conclusions: The distribution of TIL subtypes in young women’s HR+ BC varied according to race, age and grade. High stromal and intratumoral expression of Th and Tregs was associated with improved BC outcomes. Characterization of immune cell subsets could help refine the prognostic value of TILs in HR+ BC, particularly in young pts who may benefit from individualized escalated/de-escalated tx strategies.

Abstract Background: Breast cancer (BC) is the most common malignancy among women of reproductive age. Given limited data describing the conception and pregnancy experience of young BC survivors, we sought to explore these outcomes to inform counseling of women interested in future childbearing. Methods: Participants with stage 0-III BC in the Young Women’s Breast Cancer Study (NCT01468246), a multi-center, prospective cohort of women diagnosed at age ≤ 40 from 2006-2016 who reported ≥ 1 live birth from a pregnancy after diagnosis were sent a survey with investigator-developed questions focused on their first post-diagnosis live birth. Women who had been diagnosed with BC during pregnancy were excluded from this analysis. The survey assessed conception, use of assisted reproductive technology (ART), pre-implantation genetic testing (PGT), endocrine therapy (ET), and peripartum complications. Summary statistics are presented. Results: 92/119 eligible women completed the survey (response rate: 77%). Median age at diagnosis was 32 (range:17-40) years and at delivery was 37 (range: 29-47) years. Median time from diagnosis to delivery was 58 months (range: 11-154). Most women had stage 2 BC (43%, 40/92); 68% received chemotherapy (63/92); about half (51%, 47/92) were nulligravida at diagnosis. Overall, 61% of pregnancies were conceived naturally (56/92) and 39% with ART (36/92): 32% by in-vitro fertilization (IVF, 29/92), 7% with fertility medications only (6/92), and 1 with intrauterine insemination. 38% of IVF pregnancies were conceived using products from fertility preservation prior to BC treatment (11/29). Among women who used ART, 74% attempted to conceive naturally (25/36) for a median of 9 (range: 2-48) months prior to pursuing ART. The most common reasons for pursuing ART include infertility following BC treatment (33%, 12/36) and expediting conception to resume treatment (17%, 6/36). 11% of those with known inherited pathologic variant mutations underwent PGT (2/19). Reasons for not pursuing PGT included belief in more effective cancer risk reduction in the future (29%, 5/17), not being offered PGT (24%, 4/17), high cost (12%, 2/17), no interest in IVF (12%, 2/17), acceptable odds for inheriting the mutation (24%, 4/17), and belief in other risk reduction strategies (18%, 3/17); 1 woman reported ethical concerns. Of 57 women who took ET pre-pregnancy (63%), nearly all (96%, 55/57) discontinued ET &gt; 3 months prior to attempting to conceive; 1 discontinued after awareness of pregnancy. Of those who had received prior ET, 60% resumed ET (34/57) a median of 3 (range: 1-50) months after pregnancy. Among 23 women who did not resume, 13 (23%) had completed the recommended duration; the remaining 10 reported one or more of the following reasons: felt better while off (28%, 6/23), desire for another child (22%, 5/23), and desire to breastfeed (17%, 4/23). Median time to delivery was 39 (range: 28-42) weeks with 12% delivering preterm &lt; 37 weeks (11/92). 47% had a Caesarean section (43/92), with prolonged labor the most common indication (33%, 14/43). Hypertensive disorders of pregnancy (HDP, 20%, 18/92), gestational diabetes (7%, 6/92), small for gestational age (7%, 6/92), and postpartum hemorrhage (5%, 5/92) were the most common obstetrical complications. 9% of women had newborns requiring NICU admission (8/92) and 9% had low birth weight (8/92). Conclusion: Among young BC survivors with a live birth following diagnosis, most conceived naturally, with the majority who used ART first attempting natural conception. There was limited use of PGT among mutation carriers with ¼ not having been offered testing. Patient reported peripartum complications appear consistent with population norms, though the relatively higher rate of HDP bears further research. Among those yet to complete their ET, a notable proportion did not resume following delivery. This novel data may help to inform the care of young breast cancer survivors pursuing pregnancy. Citation Format: Kimia Sorouri, Tal Sella, Shoshana Rosenberg, Margaret Loucks, Kathryn Ruddy, Shari I. Gelber, Rulla M. Tamimi, Jeffrey M. Peppercorn, Lidia Schapira, Virginia F. Borges, Steven E. Come, Ellen Warner, Ann Partridge. Conception and Pregnancy Among Young Breast Cancer Survivors [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-08-05.

Abstract Background: Breast cancer (BC) is the most common malignancy in women of reproductive age, and the incidence of the disease is rising in this population. Many of these women are interested in childbearing after their BC treatment and a substantial minority will go on to have a live birth. Some will also want to breastfeed. However, there is only limited information available regarding the experience of young BC survivors breastfeeding following treatment. Methods: Participants in the Young Women’s Breast Cancer Study (YWS), a multi-center, prospective cohort study of women diagnosed with BC at age ≤ 40 years between 2006-2016, who reported at least one live birth following their diagnosis with stage 0-III BC were sent an additional survey including investigator-developed questions focused on breastfeeding after breast cancer treatment. Women who had been diagnosed with BC during pregnancy were excluded from this analysis. The survey assessed whether they breastfed, reasons for attempting and stopping breastfeeding, breastfeeding with the treated breast and untreated breast, and supports. Summary statistics, including medians and proportions, are presented. Results: Of 118 eligible women sent a survey, 92 completed the survey (78% response rate). Median age at diagnosis of BC was 32 (range: 17-40) years and at delivery was 37 (range: 29-47) years. 54% of women had attempted to breastfeed (50/92). Among those who had not, 93% noted a history of bilateral mastectomies (39/42). Additional reasons for not attempting to breastfeed included no interest regardless of BC history (5%, 2/42) and 1 woman underwent a unilateral mastectomy and did not think her supply would be sufficient. Among the women who did attempt breastfeeding, 68% had undergone lumpectomy and radiotherapy (34/50) with 85% of those women reporting that the treated breast did not produce milk (29/34). The 5 women who produced milk from the treated breast noted that the supply was substantially less than the untreated breast. To assist with breastfeeding, 76% used a pump only on the untreated breast (38/50) and 14% on both breasts (7/50). Women breastfed for a median of 5.5 (range:&lt; 1-60) months and 64% were “somewhat”/“very much” satisfied with their ability to breastfeed (32/50). The most common reasons cited for stopping breastfeeding included having completed the planned duration (36%, 18/50), to start/resume endocrine therapy (22%, 11/50), and to resume breast imaging (8%, 4/50). Among patients who had not undergone a double mastectomy, 47% recalled receiving specific information about breastfeeding after a history of breast cancer (25/53), most commonly from the oncology team (56%, 14/25), lactation consultant (48%, 12/25), or online resources (44%, 11/25). Conclusion: In the largest series to date detailing the breastfeeding experiences of young BC survivors, approximately half of young BC survivors with a successful pregnancy attempted to breastfeed. Among those who had undergone prior lumpectomy and radiotherapy, women reported no milk production or only limited supply from the treated breast. Despite these limitations, most women who attempted to breastfeed were satisfied with their ability to do so. Specific resources to support the experience of breastfeeding in BC survivors are needed. Citation Format: Tal Sella, Kimia Sorouri, Shoshana Rosenberg, Margaret Loucks, Kathryn Ruddy, Shari I. Gelber, Rulla M. Tamimi, Jeffrey M. Peppercorn, Lidia Schapira, Virginia F. Borges, Steven E. Come, Ellen Warner, Ann Partridge. Breastfeeding in Survivors of Early Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-08-06.

ImportanceCytokine storm due to COVID-19 can cause high morbidity and mortality and may be more common in patients with cancer treated with immunotherapy (IO) due to immune system activation.ObjectiveTo determine the association of baseline immunosuppression and/or IO-based therapies with COVID-19 severity and cytokine storm in patients with cancer.Design, Setting, and ParticipantsThis registry-based retrospective cohort study included 12 046 patients reported to the COVID-19 and Cancer Consortium (CCC19) registry from March 2020 to May 2022. The CCC19 registry is a centralized international multi-institutional registry of patients with COVID-19 with a current or past diagnosis of cancer. Records analyzed included patients with active or previous cancer who had a laboratory-confirmed infection with SARS-CoV-2 by polymerase chain reaction and/or serologic findings.ExposuresImmunosuppression due to therapy; systemic anticancer therapy (IO or non-IO).Main Outcomes and MeasuresThe primary outcome was a 5-level ordinal scale of COVID-19 severity: no complications; hospitalized without requiring oxygen; hospitalized and required oxygen; intensive care unit admission and/or mechanical ventilation; death. The secondary outcome was the occurrence of cytokine storm.ResultsThe median age of the entire cohort was 65 years (interquartile range [IQR], 54-74) years and 6359 patients were female (52.8%) and 6598 (54.8%) were non-Hispanic White. A total of 599 (5.0%) patients received IO, whereas 4327 (35.9%) received non-IO systemic anticancer therapies, and 7120 (59.1%) did not receive any antineoplastic regimen within 3 months prior to COVID-19 diagnosis. Although no difference in COVID-19 severity and cytokine storm was found in the IO group compared with the untreated group in the total cohort (adjusted odds ratio [aOR], 0.80; 95% CI, 0.56-1.13, and aOR, 0.89; 95% CI, 0.41-1.93, respectively), patients with baseline immunosuppression treated with IO (vs untreated) had worse COVID-19 severity and cytokine storm (aOR, 3.33; 95% CI, 1.38-8.01, and aOR, 4.41; 95% CI, 1.71-11.38, respectively). Patients with immunosuppression receiving non-IO therapies (vs untreated) also had worse COVID-19 severity (aOR, 1.79; 95% CI, 1.36-2.35) and cytokine storm (aOR, 2.32; 95% CI, 1.42-3.79).Conclusions and RelevanceThis cohort study found that in patients with cancer and COVID-19, administration of systemic anticancer therapies, especially IO, in the context of baseline immunosuppression was associated with severe clinical outcomes and the development of cytokine storm.Trial RegistrationClinicalTrials.gov Identifier: NCT04354701

Abstract Clonal hematopoiesis of indeterminate potential (CHIP), an emerging biomarker for personalized risk-directed interventions, is increased in cancer survivors. However, little is known about patient preferences for CHIP testing. We surveyed participants in a prospective cohort study of young women with breast cancer (BC). The emailed survey included an introduction to CHIP and a vignette eliciting participants’ preferences for CHIP testing, considering sequentially: population-based 10-year risk of BC recurrence, hematologic malignancy, and heart disease; increased CHIP-associated risks; current CHIP management; dedicated CHIP clinic; and hypothetical CHIP treatment. Preference changes were evaluated using the McNemar test. The survey response rate was 82.2% (528/642). Median age at time of survey was 46 years and median time from diagnosis was 108 months. Only 5.9% had prior knowledge of CHIP. After vignette presentation, most survivors (87.1%) recommended CHIP testing for the vignette patient. Presented next with CHIP-independent, population-based risks, 11.1% shifted their preference from testing to not testing. After receiving information about CHIP-associated risks, an additional 10.1% shifted their preference to testing. Preference for testing increased if vignette patient was offered a CHIP clinic or hypothetical CHIP treatment, with 7.2% and 14.1% switching preferences toward testing, respectively. Finally, 75.8% of participants desired CHIP testing for themselves. Among participants, 28.2% reported that learning about CHIP caused at least moderate anxiety. Most young survivors favored CHIP testing, with preferences influenced by risk presentation and potential management strategies. Our findings highlight the importance of risk communication and psychosocial support when considering biomarkers for future risk in cancer survivors. This trial has been registered at www.clinicaltrials.gov as #NCT01468246.

BackgroundWeight gain after a breast cancer diagnosis is common and is associated with inferior outcomes. Young survivors may be especially susceptible to weight changes given the impact of treatment on menopausal status.MethodsThe authors identified women who were diagnosed with stage 0 to III breast cancer at age 40 years or younger between 2006 and 2016 from a multicenter prospective cohort. Self‐reported weight was collected at diagnosis and at 1 year and 3 years postdiagnosis. Tumor and treatment data were obtained from medical records and patient surveys. Multinomial logistic regression was used to identify the factors associated with weight gain (≥5%) or weight loss (≥5%) versus stable weight at 1 year and 3 years postdiagnosis.ResultsThe cohort included 956 women with a median age of 37 years at diagnosis. Mean weight significantly increased over time from 66.54 ± 14.85 kg at baseline to 67.33 ± 15.53 and 67.77 ± 14.65 kg at 1 year and 3 years, respectively (p ≤ .001 for both comparisons). The proportion of women experiencing ≥5% weight gain increased from 24.8% at 1 year to 33.9% at 3 years. At 1 year, less self‐perceived financial comfort, Black race, and stage III disease were significantly associated with weight gain; at 3 years, only less self‐perceived financial comfort remained significant. Baseline overweight or obesity was significantly associated with weight loss at both time points. Chemotherapy, endocrine therapy, and treatment‐related menopause were not associated with weight change.ConclusionsOne third of young breast cancer survivors experienced clinically significant weight gain 3 years after diagnosis; however, treatment‐related associations were not observed. Age‐appropriate lifestyle interventions, including the reduction of financial barriers, are needed to prevent weight gain in this high‐risk population.

10607 Background: Young women with breast cancer who carry germline genetic pathogenic variants predisposing to breast and other cancers, including BRCA1 or BRCA2, may face unique challenges when making fertility decisions. Limited data exist on differences in fertility preferences, concerns, and preservation strategies between carriers and non-carriers. Methods: Participants in the Young Women’s Breast Cancer Study, a prospective cohort of women diagnosed with breast cancer at ≤ 40 yrs, who completed a baseline survey with a modified Fertility Issues Survey were included in this analysis. Genetic variant status was determined by medical record review complemented by survey self-report. We excluded carriers whose test date was after baseline survey completion or unknown. Fisher exact and Wilcoxon signed-rank tests were used to compare categorical and continuous variables, respectively, between carriers and non-carriers. Results: Of 1052 eligible women, 118 (11%) tested positive for a pathogenic variant (59% BRCA1, 32% BRCA2, 4% TP53, and 5% other unique pathogenic mutations) and 934 (89%) tested negative or were not tested. Carriers’ median age was 36 yrs (range 23-40) vs 37 (range 17-40, p = 0.01) in non-carriers. Similar proportions (p = 0.67) of carriers (38%, [45/118]) and non-carriers (37%, [343/934]) desired more biologic children before diagnosis. Desire declined after diagnosis similarly in both groups (carriers, 25% [29/118] vs non-carriers, 26% [242/934], p = 0.46). Among these women (n = 271), concern about passing on cancer risk to offspring was common and, although numerically higher among carriers, this difference was not statistically significant (carriers, 55% [16/29] vs non-carriers, 40% [96/242], p = 0.12). In contrast, among those not interested in or unsure about future fertility (n = 738), concern about cancer risk heritability was infrequently reported as affecting fertility decisions (carriers, 11% [9/83] vs non-carriers, 9% [56/655], p = 0.54). The same proportions (p = 0.89) of carriers (36% [43/118]) and non-carriers (36% [339/934]) were somewhat or very concerned about becoming infertile after cancer treatment, and fertility preservation strategy utilization was similar between groups (carriers, 11% [13/118] vs non-carriers, 12% [111/934], p = 0.21). Conclusions: Young women with breast cancer who carry germline pathogenic variants are similarly concerned about future fertility and as likely to pursue fertility preservation as non-carriers. Concern about cancer risk heritability was common among both carriers and non-carriers desiring future fertility, suggesting a gap between perceived and actual risk. Genetic counseling should be included in fertility discussions for all young women with breast cancer, with tailored, risk-mitigating recommendations for those who carry genetic variants.

524 Background: OFS is an important treatment component for premenopausal women with early and advanced HR+ BC and optimal efficacy may depend on complete E2 suppression with GnRHa, especially when combined with aromatase inhibitors (AI). However, standard assays lack sensitivity and accuracy at very low E2 concentrations, rendering detection of breakthrough ovarian function challenging. More informative data regarding endocrine effects of GnRHa are needed, particularly in young women who derive the most benefit from OFS yet more frequently had breakthrough E2 levels in the SOFT trial substudy, SOFT-EST. Methods: Using a prospective cohort study of women with BC diagnosed at age ≤ 40 years, we identified participants with stage I-IV HR+ BC on OFS treatment with leuprolide, goserelin or triptorelin and blood collected 1 year after diagnosis. Clinical data were obtained through surveys and medical records. Plasma estrogens were measured by liquid chromatography-tandem mass spectrometry, with a limit of detection of 0.2 pg/mL compared to 10 pg/mL with standard assays. We assessed the proportion of women on OFS with E2 > 2.72 pg/mL (10 pmol/L) and > 10 pg/mL. Patient characteristics, estrone (E1) and FSH levels, and disease-free (DFS) and overall survival (OS) were compared between those with and without elevated E2 using Fischer’s exact, Wilcoxon rank sum and log rank tests, respectively. Results: Of 84 patients who met inclusion criteria, 72 (86%) had stage I-III and 12 (14%) had stage IV BC; 25 were on OFS plus AI and 59 were on OFS plus tamoxifen (TAM). Median E2 was 3.1 pg/mL (range 0.2-30.9). 46 patients (55%) had E2 > 2.72 pg/mL, including 8 on AI and 38 on TAM; 4 (5%) had E2 > 10 pg/mL, including 1 on AI and 3 on TAM. Factors associated with E2 > 2.72 pg/mL were no prior chemotherapy, TAM and high E1 ( P ≤.05), but not age, BMI or GnRHa schedule (Table). After a median follow-up of 7 years, DFS events were seen in 6 patients with E2 > 2.72 pg/mL and 5 without ( P =.232); OS events were seen in 7 patients with E2 > 2.72 pg/mL and 5 without ( P =.608). Conclusions: More than half of young women with ER+ BC had E2 > 2.72 pg/mL on OFS, 91% of whom would not have been detected by standard assays. This may be an area amenable to intervention to improve outcomes in young women. However, larger studies are needed to elucidate the optimal E2 target on OFS and clinical implications of incomplete E2 suppression on ultrasensitive assays. [Table: see text]

Abstract Background: Extended adjuvant endocrine therapy (eET) beyond the first 5 years of ET improves long-term outcomes in breast cancer survivors. For women who remain premenopausal, evidence for benefit has only been demonstrated to date for 5 years of additional tamoxifen, after an initial 5 years of tamoxifen (from ATLAS, aTTom). There are no data available for eET among premenopausal women treated with initial adjuvant aromatase inhibition (AI) and ovarian functions suppression (OFS). Thus, there is uncertainty regarding the optimal eET regimen for young breast cancer survivors. Methods: The Young Women’s Breast Cancer Study (YWS) is a multicenter prospective cohort of women age ≤40 years newly diagnosed with breast cancer between 2006-2016. Women with stage I-III hormone receptor positive breast cancer, ≥6 years post-diagnosis without breast cancer recurrence were considered candidates for eET. Use of eET was elicited on surveys completed at 6, 7 and/or 8 years post-diagnosis, censoring for recurrence or death. Those completing ≥1 survey were eligible for analysis. Patient characteristics were compared by Chi-square test between eET users and non-users, and logistic regression applied to identify factors associated with eET use. Results: Of 667 potential eET candidates, 73.9% (493/667) returned ≥1 survey between year 6-8 and were eligible for analysis. Compared to those without a year 6-8 survey, the analytic cohort tended to be more non-Hispanic white (86.0% v. 77.6%), more financially comfortable (53.9% v. 39.5%) and more likely to have children pre-diagnosis (59.6% v. 41.4%); age and disease characteristics were similar. Overall, 59.6% (294/493) reported any eET use, with use declining over time from 56.9% (265/466) to 51.4% (219/426) to 46.8% (162/346) at years 6, 7 and 8 post-diagnosis, respectively. Among eET users (n=294), tamoxifen monotherapy was the most common approach (76.9%, 226/294), followed by AI monotherapy (22.1%, 65/294, presumably women who transitioned into menopause), AI-OFS (7.1%, 21/294) and tamoxifen-OFS (3.1%, 9/294). Women diagnosed after 2012 were as likely to receive eET as those diagnosed 2006-2011 (59.4%, 117/197 v. 59.8%, 177/296 p=0.928), however eET more often included AI, with or without OFS (41.0% v. 18.6%, p&lt;0.001), or OFS (17.9% v. 7.3%, p=0.005) in later years. In multivariable analysis, increasing age (per year odds ratio [OR]: 1.10, 95% confidence interval [CI]: 1.04-1.15, p&lt;0.001), higher stage (II v. I: OR: 2.85, 95% CI: 1.81-4.48, p&lt;0.001; III v. I: OR: 3.73, 95% CI: 1.87-7.42, p&lt;0.001) and receipt of chemotherapy (OR: 3.50, 95% CI: 2.08-5.91, p&lt;0.001) were independently significantly associated with any eET use, while women not of white non-Hispanic race/ethnicity were less likely to report eET use (OR: 0.49, 95% CI: 0.28-0.87, p=0.014). Rates of pregnancy in years 1-5 did not differ between eET users and non-users (10.0%, 29/291 v. 8.7%, 17/195, p=0.645) Conclusion: The majority of eligible young breast cancer survivors in the YWS have received eET despite limited data regarding its utility in this population. Heterogeneity exists regarding strategies utilized, and while some factors associated with eET use appear to reflect appropriate risk-based care, such as stage and receipt of chemotherapy, others, including age and race, suggest disparate uptake. Clinical studies are needed in order to determine the optimal approach to eET for young women with a history of early stage hormone receptor-positive breast cancer who remain premenopausal following 5 years of ET. Ensuring risk and preference-based uptake of eET should be a priority. Citation Format: Tal Sella, Yue Zheng, Shoshana M Rosenberg, Kathryn J Ruddy, Shari I Gelber, Rulla M Tamimi, Jeffrey M Peppercorn, Lidia Schapira, Virgina F Borges, Steven E Come, Lisa A Carey, Eric P Winer, Ann H Partridge. Extended adjuvant endocrine therapy in a longitudinal cohort of young breast cancer survivors [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD13-10.

Background Fear of cancer recurrence (FCR) is more intense in younger women. Because FCR is a powerful determinant of quality of life, identifying those at risk for persistently elevated FCR can inform timing of interventions. Methods A total of 965 women with stage 0 to stage III breast cancer enrolled in the Young Women's Breast Cancer Study, a prospective cohort of women diagnosed with breast cancer at age ≤40 years, completed the 3‐item Lasry Fear of Recurrence Index. Group‐based trajectory modeling was used to classify distinct FCR patterns from baseline through 5 years post‐diagnosis. Multinomial logistic regression was used to identify patient, disease, and treatment characteristics associated with each trajectory. Results Five FCR trajectories were identified with the majority of participants having moderate (33.1%) or high FCR (27.6%) that improved over time. A total of 6.9% participants had moderate FCR that worsened, whereas 21.7% had high FCR at baseline that remained high throughout. In the fully adjusted multinomial model, stages II and III (vs stage I) were associated with higher odds of being in the high/stable trajectory, whereas stage 0 (vs I), being financially comfortable (vs not comfortable), was associated with lower odds of being in the high/stable trajectory. White (vs non‐White) was associated with higher odds of being in a trajectory that improved over time. Conclusions Although FCR improves over time for many young women with breast cancer, approximately one‐third had FCR that was severe and did not improve or worsened over 5 years after diagnosis. Ongoing monitoring is warranted, with early referral to mental health professionals indicated for those at highest risk for unresolved FCR. Lay Summary Fear of recurrence is common among young women with breast cancer. The authors followed a large cohort of young women diagnosed with breast cancer when they were 40 years of age and younger, and found 5 distinct trajectories that show moderate and severe fears do not always improve over time and may require targeted mental health intervention.