Dataset Information

Investigating confounders of the association between survival and adjuvant radiation therapy after breast conserving surgery in a sample of elderly breast Cancer patients in Appalachia.

ABSTRACT:

Background

To explain the association between adjuvant radiation therapy after breast conserving surgery (BCS RT) and overall survival (OS) by quantifying bias due to confounding in a sample of elderly breast cancer beneficiaries in a multi-state region of Appalachia.

Methods

We used Medicare claims linked registry data for fee-for-service beneficiaries with AJCC stage I-III, treated with BCS, and diagnosed from 2006 to 2008 in Appalachian counties of Kentucky, Ohio, North Carolina, and Pennsylvania. Confounders of BCS RT included age, rurality, regional SES, access to radiation facilities, marital status, Charlson comorbidity, Medicaid dual status, institutionalization, tumor characteristics, and surgical facility characteristics. Adjusted percent change in expected survival by BCS RT was examined using Accelerated Failure Time (AFT) models. Confounding bias was assessed by comparing effects between adjusted and partially adjusted associations using a fully specified structural model.

Results

The final sample had 2675 beneficiaries with mean age of 75, with 81% 5-year survival from diagnosis. Unadjusted percentage increase in expected survival was 2.75 times greater in the RT group vs. non-RT group, with 5-year survival of 85% vs 60%; fully adjusted percentage increase was 1.70 times greater, with 5-year rates of 83% vs 71%. Quantification of incremental confounding showed age accounted for 71% of the effect reduction, followed by tumor features (12%), comorbidity (10%), dual status(10%), and institutionalization (8%). Adjusting for age and tumor features only resulted in only 4% bias from fully adjusted percent change (70% change vs 66%).

Conclusion

Quantification of confounding aids in determining covariates to adjust for and in interpreting raw associations. Substantial confounding was present (60% of total association), with age accounting for the largest share (71%); adjusting for age plus tumor features corrected for most of the confounding (4% bias). The direct effect of BCS RT on OS accounted for 40% of the total association.

SUBMITTER: Camacho F

PROVIDER: S-EPMC6918701 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Publications

Investigating confounders of the association between survival and adjuvant radiation therapy after breast conserving surgery in a sample of elderly breast Cancer patients in Appalachia.

Camacho Fabian F Anderson Roger R Kimmick Gretchen G

BMC cancer 20191217 1

<h4>Background</h4>To explain the association between adjuvant radiation therapy after breast conserving surgery (BCS RT) and overall survival (OS) by quantifying bias due to confounding in a sample of elderly breast cancer beneficiaries in a multi-state region of Appalachia.<h4>Methods</h4>We used Medicare claims linked registry data for fee-for-service beneficiaries with AJCC stage I-III, treated with BCS, and diagnosed from 2006 to 2008 in Appalachian counties of Kentucky, Ohio, North Carolin ...[more]

PMID: 31847855

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Project description:We aimed to evaluate the standard of care of adjuvant radiotherapy (RT) after breast-conserving surgery (BCS) in elderly female patients (≥65 years) treated outside of clinical trials and to identify potential factors related to the omission of RT and the interaction with endocrine therapy (ET). All women treated with BCS at two major breast centers between 1998 and 2014 were evaluated. Data were provided by the Tumor Registry Munich. Survival analyses were conducted using the Kaplan-Meier method. Prognostic factors were identified using multivariate Cox regression analysis. The median follow-up was 88.4 months. Adjuvant RT was performed in 82% (2599/3171) of patients. Irradiated patients were younger (70.9 vs. 76.5 years, p < 0.001) and were more likely to receive additional chemotherapy (p < 0.001) and ET (p = 0.014). Non-irradiated patients more often had non-invasive DCIS tumors (pTis: 20.3% vs. 6.8%, p < 0.001) and did not undergo axillary surgery (no axillary surgery: 50.5% vs. 9.5%, p < 0.001). Adjuvant RT was associated with improved locoregional tumor control after BCS in invasive tumors (10-year local recurrence-free survival (LRFS): 94.0% vs. 75.1%, p < 0.001, 10-year lymph node recurrence-free survival (LNRFS): 98.1% vs. 93.1%, p < 0.001). Multivariate analysis confirmed significant benefits for local control with postoperative RT. Furthermore, RT led to increased locoregional control even in patients who received ET (10-year LRFS 94.8% with ET + RT vs. 78.1% with ET alone, p < 0.001 and 10-year LNRFS: 98.2% vs. 95.0%, p = 0.003). Similarly, RT alone had significantly better locoregional control rates compared to ET alone (10-year LRFS 92.6% with RT alone vs. 78.1% with ET alone, p < 0.001 and 10-year LNRFS: 98.0% vs. 95.0%, p = 0.014). The present work confirms the efficacy of postoperative RT for breast carcinoma in elderly patients (≥65 years) treated in a modern clinical setting outside of clinical trials, even in patients who receive ET.

Project description:Lipofilling has regenerative properties used to improve deformities after breast conserving surgery. Our hypothesis is that there is inadequate data to ensure that lipofilling does not increase locoregional cancer recurrence after breast conserving surgery. A PRISMA comprehensive literature review was conducted of articles published prior to October 2019 investigating recurrence in patients who underwent lipofilling after breast conserving surgery. All forms of breast conserving surgery, fat grafting, and injection intervals were included. Patients undergoing mastectomy were excluded. Requirements to define lipofilling as "safe" included (I) a defined interval between resection and lipofilling; (II) a minimum follow-up period of 6 years from tumor resection; (III) a minimum follow-up period of 3 years from lipofilling; (IV) presence of a control group; (V) controls matched for ER/PR/Her-2; (VI) a sub-group analysis focusing on ER/PR/Her-2; (VII) adequate powering. Nineteen studies met inclusion criteria. The range in time from breast conserving surgery to fat injection was 0-76 months. The average time to follow-up after lipofilling was 23 days-60 months. Two studies had a sufficient follow-up time from both primary resection and from lipofilling. Seventeen of the nineteen studies specified the interval between resection and lipofilling, but there is currently no consensus regarding how soon lipofilling can be performed following BCS. Eight studies performed a subgroup analysis in cases of recurrence and found recurrence after lipofilling was associated with number of positive axillary nodes, intraepithelial neoplasia, high grade histology, Luminal A subtype, age <50, Ki-67 expression, and lipofilling within 3 months of primary resection. Of the eleven studies that included a comparison group, one matched patient for Her-2 and there was a statistically significant difference in Her-2 positive cancers in the study arms of two articles. Several studies deemed lipofilling "safe," two showed association of lipofilling and local recurrence, and most studies concluded that further research was needed. Insufficient and contradictory data exists to demonstrate the safety of lipofilling after breast conserving surgery. A multicentered, well designed study is needed to verify the safety of this practice.

Dataset Information

Investigating confounders of the association between survival and adjuvant radiation therapy after breast conserving surgery in a sample of elderly breast Cancer patients in Appalachia.

Background

Methods

Results

Conclusion

Publications

Investigating confounders of the association between survival and adjuvant radiation therapy after breast conserving surgery in a sample of elderly breast Cancer patients in Appalachia.

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