Gastrointestinal Cancer

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SU_5_2052 - An analysis of toxicity and outcomes in older versus younger rectal cancer patients treated with trimodality therapy

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

An analysis of toxicity and outcomes in older versus younger rectal cancer patients treated with trimodality therapy
J. K. Wong, E. Handorf, R. Jain, E. Zhang, T. Shaikh, E. Dotan, and J. E. Meyer; Fox Chase Cancer Center, Philadelphia, PA

Purpose/Objective(s): Trimodality therapy (TMT), neoadjuvant chemoradiation followed by surgical resection, is standard of care for locally advanced rectal cancer, improving outcomes versus surgery alone. However, older patients are not well represented in studies and data are limited in this population. This study analyzed toxicity patterns and outcomes in older versus younger rectal cancer patients treated with TMT.

Materials/Methods: We included patients at a single institution identified to undergo TMT for histologically confirmed locally advanced rectal adenocarcinoma. Patients receiving upfront surgery or short course radiation were excluded. A classification and regression tree (CART) analysis was used to determine an ideal age cutoff. The primary endpoint was acute toxicity, with secondary endpoints of treatment modification, recurrence free survival (RFS), and pathologic complete response (pCR) rate. Wilcoxon and Fisher’s exact tests were used to determine the association between age group and outcomes. RFS was assessed with the Kaplan-Meier method.

Results: A total of 123 patients were included, ages 30-92, with 43 months median follow up. The older (age >=65, n=41) and younger (age<65, n=82) groups were well balanced with respect to gender, race, T and N stage, tumor location, chemotherapy regimen, and radiation technique. However, the older population had worse pretreatment performance status (PS) and higher Charlson Comorbidity Index (CCI) score. Older patients had significantly more hospitalizations (17.1% vs 2.4%, p = 0.006) and more hematologic toxicity (p=0.006). There was no significant difference in non-hematologic toxicity, decrease in PS, or weight loss during treatment. There was a higher rate of chemotherapy deintensification (39.0% vs 8.5%, p=0.0001), but no significant difference in rates of radiation treatment breaks (26.8% vs 18.3%, p=0.35) or rates of surgical resection (95.1% vs 96.3%, p=0.99). There was a significant difference in RFS between the two groups (p=0.012), with 3 year RFS 76% in the older group and 90% in the younger. Even when adjusted for pretreatment PS (p=0.033) or CCI score (p=0.049) the difference in RFS between older and younger patients persisted. There was no significant difference in pCR rates (30.3% vs 35.9%, p=0.68).

Conclusion: Older rectal cancer patients treated with TMT experienced more hematologic toxicity and hospitalizations during treatment, with associated increased rates of chemotherapy deintensification but no significant difference in radiation or surgical therapy. These differences may have contributed to decreased RFS in older patients. Decreased RFS persisted after PS and comorbidity adjustments, indicating the strength of age as a predictor of RFS. As this is a novel finding in rectal cancer, additional studies are warranted to evaluate the appropriate approach to older patients with this disease.

Author Disclosure: J.K. Wong: None. E. Handorf: None. R. Jain: None. E. Zhang: None.

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