Non-Operative Management of Rectal or Anal Canal Adenocarcinoma: National Cancer Database Analysis of the Impact of Disease, Treatment, and Social Determinants of Health on Overall Survival

PURPOSE/OBJECTIVE(S)

For select patients with rectal or anal canal adenocarcinoma (RA-ACA), a non-operative management (NOM) strategy utilizing definitive radiotherapy (RT) has emerged as an option with the goal to improve quality of life compared with surgical management while maintaining similar oncologic outcomes. Disease and treatment characteristics as well as social determinants of health have been associated with access to care and health outcomes, and we hypothesized that such factors would impact overall survival (OS) amongst patients who received a NOM approach. The purpose of this study was to explore the influence of patient demographics, disease characteristics, and social determinants of health on OS amongst those receiving NOM utilizing the National Cancer Database (NCDB).

MATERIALS/METHODS

We identified patients at least 18 of years of age diagnosed with clinical stage 1-3 RA-ACA from 2004-2018. The NOM cohort included patients who received RT and either refused surgery or surgery was not recommended in their treatment. Patients were excluded if receipt of chemotherapy or RT were unknown, received RT to a site outside of the pelvis, or received palliative-intent treatment. OS was estimated using the Kaplan-Meier method. Univariable and multivariable (MVA) Cox proportional hazards model was used to assess characteristics associated with OS. Analyses were performed using STATA (version 17, College Station, TX). A p<0.05 was considered statistically significant.

RESULTS

A total of 12,409 patients were identified as the NOM cohort. The median OS was 48.8 months (95% CI: 46.8-50.6). On MVA, variables associated with poorer OS included age ≥ 70 vs 50-69, male sex, Charlson-Deyo Score ≥ 1 vs 0, insurance status (no insurance, Medicaid or Medicare vs. private), geographical region (South, Midwest or West vs. Northeast), rural urban density vs metro/urban, treatment in a community facility vs academic, year of diagnosis (2004-2011 vs. 2012-2018), clinical T4 vs T1, clinical N1 or N2 vs N0, and grade 3 vs 1 (all p<0.05). Treatment with a RT dose < 45 Gy vs. 45-54 Gy (HR: 2.24, 95% CI: 2.07-2.44), but not > 55 Gy vs. 45-54 Gy, and omission of chemotherapy (HR: 1.28, 95% CI: 1.16-1.43) were associated with poorer OS.

CONCLUSION

Patient, disease, treatment, and social determinants of health may influence OS amongst patients with RA-ACA who receive a NOM approach. Further work is needed to determine if the influence on OS can be explained, in part, by patients' lack of access to the intense surveillance necessary and/or the potential need for subsequent surgical management. Heightened awareness of these differential outcomes is needed to assist in patient selection and to successfully address barriers in access to optimize outcomes for patients who receive NOM.

Dosimetric Risk Estimation of Chest Wall Pain Following 5-Fraction Lung Stereotactic Body Radiotherapy

PURPOSE/OBJECTIVE(S)

Development of chest wall pain (CWP) following lung stereotactic body radiotherapy (SBRT) is a known toxicity, particularly for peripheral lesions. While CW V30 has been most consistently associated with development of post-SBRT CWP, existing series included heterogeneous dose-fractionation regimens, most commonly 48-54 Gy in 3-4 fractions. The present study aims to identify clinical and dosimetric variables associated with development of CWP among patients treated with 5 fraction lung SBRT.

MATERIALS/METHODS

Intradepartmental quality assurance database of SBRT patients was queried to identify lung targets treated to a minimum of 45 Gy in 5 fractions. Retrospective chart and plan reviews were performed on these cases to collect patient, tumor, and treatment-related data, selecting for patients with peripheral lesions (any histology), and recording presence or absence of CWP during or following SBRT. Patients with less than 6 months of post-SBRT clinical follow-up were excluded. The CW was defined as a 2 cm expansion of the ipsilateral lung (inclusive of intercostal musculature, ribs, and superficial soft tissue). Logistic regression analyses were performed on continuous and nominal data to determine statistically significant (p<0.05) correlations between clinical (age, gender, known osteopenia/osteoporosis, diabetes, prior thoracic radiotherapy, lesion distance to CW), treatment (interval of SBRT delivery, dose prescribed), and dosimetric (Dose to 0.1/1/5/10cc; V30, V40) factors with CWP.

RESULTS

Between February 2011 and January 2022, 93 patients were identified for inclusion in the present analysis, treated to 100 total lesions in 99 courses of treatment. Median patient age was 75 years (range 34-90), 48 (52%) were female, and 29 (of 99 treatment courses; 29%) had received prior thoracic radiotherapy. Median SBRT dose was 50 Gy (45-60), delivered over a median of 9 days (4-18). At a median post-SBRT follow-up of 21 months, 11 patients developed CWP at a median of 9 months post-SBRT (0-32). Statistically significant correlations were identified between CWP and known pre-existing osteopenia or osteoporosis, target distance to CW, and CW D0.1cc, D1cc, D5cc, and D10cc, but not CW V30 or V40. Crude risk of CWP for selected clinically practical dose-volume thresholds are presented in Table 1: CONCLUSION: For patients treated with lung SBRT in 5 fractions, dose to CW volume thresholds appears to correlate more closely than V30 or V40 for CWP estimation. Further investigation and validation of optimal CW volume thresholds, as well as integration of pre-existing condition clinical factors in risk estimation, appears warranted.

Secondary breast angiosarcoma following accelerated partial breast irradiation with intracavitary multicatheter applicator brachytherapy

PURPOSE

Secondary angiosarcoma of the breast is a rare complication of breast radiotherapy and is associated with a poor prognosis. There are many reported cases of secondary angiosarcoma following whole breast irradiation (WBI), however development of secondary angiosarcoma following brachytherapy-based accelerated partial breast irradiation (APBI) is not as well characterized.

METHODS AND MATERIALS

We reviewed and reported a case of a patient who developed secondary angiosarcoma of the breast following intracavitary multicatheter applicator brachytherapy APBI.

RESULTS

A 69-year-old female was originally diagnosed with T1N0M0 invasive ductal carcinoma of the left breast and treated with lumpectomy followed by adjuvant intracavitary multicatheter applicator brachytherapy APBI. Seven years following her treatment, she developed secondary angiosarcoma. However, the diagnosis of secondary angiosarcoma was delayed due to nonspecific imaging findings and a negative biopsy.

CONCLUSIONS

Our case highlights the need for secondary angiosarcoma to be considered in the differential diagnosis when patients present with symptoms such as breast ecchymosis and skin thickening following WBI or APBI. Prompt diagnosis and referral to a high-volume sarcoma treatment center for multidisciplinary evaluation is vital.