The prognostic value of an early response in chemoradiation of locally advanced rectal cancer.
e14134 Background: Preoperative chemoradiation is standard treatment of locally advanced rectal cancer, and there is an obvious need for new methods of assessing the effect. Evaluation by clinical examination with endoscopy is controversial. In most papers the assessment of effect has been performed after the end of treatment. The aim of the present study was to investigate the clinical value of an examination during chemoradiation. Methods: The study included 128 patients with histopathologically verified rectal cancer. Further inclusion criteria were a T3 tumor with a circumferential margin ≤ 5 mm by MRI or a T4 tumor, a distance of < 10 cm from the anal verge and localized diseased only by abdominal and chest CT scan. The treatment was 50.4 Gy/28 fractions or the same treatment with the addition of endorectal brachytherapy 10 Gy/2 fractions in a randomized trial. The concomitant chemotherapy was UFT 300 mg/m2 and L-leucovorin 22.5 mg daily. Both drugs were given five days a week. Clinical examination with endoscopy was performed week 4 during treatment. The clinical effect was classified into complete response (CR) or not complete response with clinical residual tumor (NCR). The patients were operated eight weeks after end of treatment and the pathological tumor response was classified according to Mandard (TRG). Results: CR was found in 14% of the patients. Comparison with TRG showed that 82% with CR had TRG1 as compared to the NCR group where only 9% had TRG1 (p<10-4). The risk of lymph node metastasis was also different with 94% pN0 in the group with CR compared to 57% in the NCR group (p=0.02). The rate of CR translated to a major difference in the risk of recurrence (local and distant). No patients with CR experienced recurrence as compared to 19% in the NCR group (p<0.05). The CR also correlated with cancer specific survival. None of the patients with CR died from rectal cancer with a median observation time of 36 months compared to 30% in the NCR group. Conclusions: CR is a major prognostic parameter in locally advanced rectal cancer treated with chemoradiation. Early CR should be considered in the selection of patients for Watchful Waiting.