RESUMEN
BACKGROUND: Neoadjuvant CRT may lead to significant tumor regression in patients with rectal cancer. Different CRT regimens with consolidation chemotherapy may lead to increased rates of complete tumor regression. The purpose of this study was to understand tumor metabolic activity following two different neoadjuvant CRT regimens using sequential PET/CT imaging in two different intervals following RT. METHODS: Patients with cT2-4 N0-2 M0 rectal cancer treated by standard CRT (54Gy and 2 cycles of 5FU-based chemotherapy) or extended CRT (54Gy and 6 cycles of 5FU-based chemotherapy) underwent sequential PET/CT imaging at baseline, 6 weeks and 12 weeks from radiation completion. RESULTS: 99 patients undergoing standard CRT were compared to 12 patients undergoing CRT with consolidation chemotherapy. Patients treated with consolidation CRT had increased rates of complete clinical or pathological response (66 % vs. 23 %; p < 0.001). SUVmax variation between baseline and 6 weeks (88 % vs. 63 %; p < 0.001) and between baseline and 12 weeks (90 % vs. 57 %; p < 0.001) were significantly more pronounced among patients undergoing extended CRT with consolidation chemotherapy. An increase in SUVmax between 6 and 12 weeks was observed in 51 % of patients undergoing standard and 18 % of patients undergoing consolidation CRT (p = 0.04). CONCLUSIONS: Most of the reduction in tumor metabolism after neoadjuvant CRT occurs within the first 6 weeks from RT completion. In patients undergoing CRT with consolidation chemotherapy, tumors are less likely to regain metabolic activity between 6 and 12 weeks. Therefore, assessment of tumor response may be safely postponed to 12 weeks in patients undergoing extended CRT with consolidation chemotherapy. TRIAL REGISTRATION: NCT00254683.
Asunto(s)
Adenocarcinoma/terapia , Antineoplásicos/farmacología , Quimioradioterapia/métodos , Quimioterapia de Consolidación/métodos , Terapia Neoadyuvante/métodos , Neoplasias del Recto/terapia , Adenocarcinoma/diagnóstico por imagen , Anciano , Método Doble Ciego , Femenino , Fluorouracilo/administración & dosificación , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Tomografía de Emisión de Positrones , Neoplasias del Recto/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Resultado del TratamientoRESUMEN
BACKGROUND: Local excision may offer the possibility of organ preservation for the management of select patients after neoadjuvant chemoradiation. The oncological outcomes of this strategy have been largely associated with the risk of nodal metastases. Therefore, in addition to final ypT status, baseline staging has been suggested to potentially influence the outcomes of this treatment modality. OBJECTIVE: The aim of this study is to compare the pathological and oncological outcomes of patients following neoadjuvant chemoradiation and incomplete clinical response managed by transanal endoscopic microsurgery according to baseline staging. DESIGN: This study is a retrospective review of prospectively collected data. SETTINGS: The study was conducted at a single center. PATIENTS: Forty-six patients with distal rectal cancer cT2-4N0-2M0 underwent 5-fluorouracil-based neoadjuvant chemoradiation. Assessment of response was performed at least 8 weeks from radiotherapy completion. Patients with a complete clinical response were not operated on immediately. Patients with an incomplete clinical response were managed by surgery. Those with small (≤3 cm) residual cancers (ycT1-2N0M0) were managed by transanal endoscopic microsurgery. MAIN OUTCOME MEASURES: Patients undergoing local excision following chemoradiation were compared according to baseline staging. RESULTS: Fifteen patients (32%) were cT2N0 at baseline. Final ypT status was ypT0 in 3 (20%) patients, ypT1 in 2 (13%) patients, ypT2 in 9 (60%) patients, and ypT3 in 1 (7%) patient. There were no differences in final ypT status in comparison with patients with baseline cT3-4 or cN+ undergoing chemoradiation followed by transanal endoscopic microsurgery (p = 0.38). Local recurrence was observed in 1 patient with baseline cT2N0 (7%) and in 7 patients (23%) with stage II and III (p = 0.18). LIMITATIONS: This study was limited by the short follow-up, its limited sample size, and its retrospective and nonrandomized nature. CONCLUSIONS: Patients with baseline cT2N0 that do not develop complete response to chemoradiation (ycT0-2N0; ≤3 cm) frequently present unfavorable pathological features for transanal local excision (ypT2 or 3 in >66%). In the presence of incomplete clinical response following chemoradiation, patients with baseline cT2N0 have pathological and oncological outcomes similar to patients with baseline stage II or III and are probably not ideal candidates for local excision (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A159).