Gastrointestinal Cancer

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SU_2_2020 - Radical Therapeutic Strategies for Primary Unresectable Rectal Cancer- Radiochemotherapy, Conventional Radiation Therapy, and Hyperfractionated Radiation Therapy

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

Radical Therapeutic Strategies for Primary Unresectable Rectal Cancer- Radiochemotherapy, Conventional Radiation Therapy, and Hyperfractionated Radiation Therapy
M. Kraszkiewicz, A. Napieralska, J. Wydmanski, B. A. Maciejewski, and W. Majewski; Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch, Gliwice, Poland

Purpose/Objective(s): To compare the treatment outcome in patients with primary unresectable rectal cancer treated with radiochemotherapy, conventional radiotherapy and hyperfractionated accelerated radiotherapy.

Materials/Methods: Clinical, retrospective material consists of 145 patients (pts) with primary unresectable, locally advanced rectal cancer cT4N0/N+/M0 treated from 2000 to 2016. The aim of this treatment was tumor downstaging enabling further radical resection. There were 105 men (72%) and 40 women (28%). The median age in RT group was 63 years (range 33-84), in RTCT group it was 59 years (range 26-76) (p=0.045). Pts in RTCT group had slightly better performance status (PFS) than in RT group i.e. ZUBROD 0, 1, 2 was scored in 60% vs 44%, 40% vs 52%, 0% vs 4% (p=0.054) and more often suspected regional lymph nodes 61% vs 40% (p=0,01). Other factors: tumor volume, location and sex were not significantly different between the groups. Data were subdivided initially into two groups: (RT) pts who received radiotherapy only (n=73) and (RTCT) treated with radiochemotherapy (n=72). In the RT group two other subgroups were described: Hyperfractionated (HF) with a total dose (TD) of 66 Gy in 1.5 Gy fractions twice a day or Conventional (CF) with a TD of 60-66 Gy in 2 Gy fractions. In the RTCT group TD of 54 Gy with 1.8 Gy was given concurrently with two courses of 5-Fu (325 mg/m2 or 375/m2)+ LV (20 mg/m2) in week 1 and 5 of therapy. Treatment efficacy was compared between RT and RTCT, then in 3 subgroups with different fractionation schemes. The outcomes were estimated based on 4 endpoints: objective response (OR) i.e. the sum of complete and partial regression, resectability rate (RR), local tumor control (LTC) and overall survival (OS). Statistical methods used for OR and RR were χ2 test and logistic regression, and for LTC and OS it was Kaplan-Meier survival analysis and Cox regression. The differences between groups were estimated with log-rank test.

Results: Objective response rate was higher in RTCT than in RT group (75% vs 60%, p=0,065). The RR was also higher in RTCT than in RT group (64% vs 37%, p=0,0012). Five year LTC was 68% in RTCT, and only 34% in RT (p=0,000). After R0 resection, RTCT group experienced no locoregional recurrence compared with 22% in RT group. Five-year OS was respectively: 52% vs 27% (p=0,002).In a subgroup analysis: RTCT had best outcome in LTC compared to two other schemes: 68% vs HF: 42% and CF: 25%. Five-year OS in RTCT (52%) was much better from CF (17%) but showed only a trend compared to HF 36% (p=0,057).

Conclusion: Radiochemotherapy resulted in better outcome than radiotherapy alone regarding objective response, surgical resectability, local control, and overall survival and should be considered as optimal choice for all suitable patients because of its high local effectiveness. In patients not suitable for radiochemotherapy, hyperfractionated radiotherapy could be considered for its moderately better efficacy than conventional radiotherapy.

Author Disclosure: M. Kraszkiewicz: None. A. Napieralska: None. J. Wydmanski: None. B.A. Maciejewski: None. W. Majewski: None.

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