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For patients with breast cancer, delays in chemotherapy initiation have been adversely associated with recurrence and survival. We evaluated patient-level factors associated with delayed chemotherapy initiation, from both diagnosis and surgery, in a community-based cohort of women with early-stage breast cancer. For the Optimal Breast Cancer Chemotherapy Dosing study, we identified a cohort of 34,109 women diagnosed with stage I-IIIA breast cancer at two U.S. integrated healthcare delivery systems between 2004 and 2019. We used logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI) to identify patient factors associated with delays in chemotherapy initiation after diagnosis (≥90 days) and surgery (≥60 days). Among 10,968 women receiving adjuvant chemotherapy, 21.1% experienced delays in chemotherapy initiation after diagnosis and 21.3% after surgery. Older age, non-Hispanic Black and Hispanic race and ethnicity, and ER+ and/or PR+ disease were associated with increased likelihood of delays to chemotherapy initiation after diagnosis and surgery. People diagnosed in 2012-2019 (vs. 2005-2011), with a higher grade and larger tumor size were less likely to experience delays. Other factors were associated with a higher likelihood of delays specifically from diagnosis (earlier stage, mastectomy vs. breast-conserving surgery), or surgery (higher comorbidity, increased nodal number). Women diagnosed with breast cancer who were at highest risk of progression and recurrence were less likely to experience delays in chemotherapy initiation after diagnosis and surgery. Understanding reasons for chemotherapy delays beyond patient factors may be potentially important to reduce risk of breast cancer recurrence and progression., (© 2024 UICC.)

Purpose: The National Comprehensive Cancer Network (NCCN) guidelines recommend a variety of drug combinations with specific administration schedules for the treatment of early-stage breast cancer, allowing physicians to deliver treatments recognizing individual patient complexities, including comorbidities, and patient-physician preference. While use of guideline regimens has shifted over time, there is little data to describe changes in how treatment for early-stage breast cancer has evolved over time., Methods: In a cohort of 34,109 women treated for stage I-IIIA breast cancer between 2006-2019 at Kaiser Permanente Northern California and Kaiser Permanente Washington, we present the changes in chemotherapy regimens over time, and explore use of NCCN-guideline regimens (GR), guideline regimens used when said regimens were not included in guidelines, referred to as time-discordant regimens (TDR), and non-guideline regimens (NGR). Results are presented by drug combination and over time., Results: Among 12,506 women receiving chemotherapy, 77.4% (n = 9681) received GRs, 9.1% (n = 1140) received TDRs, and 13.5% (n = 1685) received NGRs. In 2006, AC-T (cyclophosphamide-doxorubicin, paclitaxel) was the most common regimen, with TC (cyclophosphamide-docetaxel) becoming the most prevalent by 2019. NGRs were more common in cyclophosphamide-methotrexate-5-fluorouracil (CMF); cyclophosphamide-doxorubicin-paclitaxel-trastuzumab (ACTH); and paclitaxel-trastuzumab (TH). The use of GR has increased over time (p-trend < 0.001), while use of NGR (both in terms of administration schedule and drug combination) and TDR have decreased, although patterns vary by drug combination., Conclusion: Chemotherapy delivery has changed markedly over time, with a move toward more use of GR. These data are important for understanding the landscape of chemotherapy delivery in community healthcare settings., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Guidelines informing chemotherapy regimen selection are based on clinical trials with participants who do not necessarily represent general populations with breast cancer. Understanding who receives nonguideline regimens is important for understanding real-world chemotherapy administration and how it relates to patient outcomes., Methods: Using data from the Optimal Breast Cancer Chemotherapy Dosing (OBCD) study, based at Kaiser Permanente Northern California (2006-2019) and Kaiser Permanente Washington (2004-2015), we use logistic regression to examine the associations between patient characteristics and receipt of nonguideline chemotherapy regimens among 11,293 women with primary stage I to IIIA breast cancer receiving chemotherapy., Results: The use of nonguideline regimens was strongly associated with several factors, including older age [≥80 vs. 18-39 years: OR, 5.25; 95% confidence interval (CI), 3.06-9.00; P-trend = 0.002] and HER2 status (HER2+ vs. HER2-: OR, 3.44; 95% CI, 3.06-3.87) and was less likely in women with larger tumor size (>5 cm vs. 0.1 to ≤0.5 cm: OR, 0.56; 95% CI, 0.36-0.87; P-trend = 0.01) and diagnosed in later years (2012-2019 vs. 2005-2011: OR, 0.80; 95% CI, 0.71-0.90). Factors associated varied by type of nonguideline regimens. For example, women with comorbidity and older age were more likely to receive nonguideline drug combinations in particular, whereas women with larger tumor size were less likely to receive nonguideline administration schedules., Conclusions: Nonguideline chemotherapy regimens are more likely in certain patient populations., Impact: These associations highlight that vulnerable patient populations may be less likely to receive guideline care, and thus, real-world studies are essential for understanding how the use of nonguideline regimens impacts patient outcomes in these groups., (©2024 American Association for Cancer Research.)

Background: Little is known about how use of chemotherapy has evolved in breast cancer patients. We therefore describe chemotherapy patterns for women with stage I-IIIA breast cancer in the Optimal Breast Cancer Chemotherapy Dosing (OBCD) Study using data from KPNC (Kaiser Permanente Northern California) and KPWA (Kaiser Permanente Washington)., Findings: Among 33,670 women, aged 18 + y, diagnosed with primary stage I-IIIA breast cancer at KPNC and KPWA from 2006 to 2019, we explored patterns of intravenous chemotherapy use, defined here as receipt of intravenous cytotoxic drugs and/or anti-HER2 therapies. We evaluated trends in chemotherapy receipt, duration over which chemotherapy was received, and number of associated infusion visits. In secondary analyses, we stratified by receipt of anti-HER2 therapies (trastuzumab and/or pertuzumab), given their longer duration. 38.9% received chemotherapy intravenously, declining from 40.2% in 2006 to 35.6% in 2019 (p-trend < 0.001). Among 13,089 women receiving chemotherapy, neoadjuvant treatment increased (4.1-14.7%; p-trend < 0.001), as did receipt of anti-HER2 therapies (20.8-30.9%) (p-trend < 0.001). The average treatment duration increased (5.3 to 6.0 months; p-trend < 0.001), as did the number of infusion visits (10.8 to 12.5; p-trend < 0.001). For those receiving anti-HER2 therapies, treatment duration and average number of visits decreased; among those not receiving anti-HER2 therapies, number of visits increased, with no change in duration., Conclusions: While the prevalence of chemotherapy receipt has decreased over time, the use of neoadjuvant chemotherapy has increased, as has use of anti-HER2 therapies; duration and number of administration visits have also increased. Understanding these trends is useful to inform clinical and administrative planning., (© 2024. The Author(s).)