PREOPERATIVE ADJUVANT RADIATION WITH CHEMOTHERAPY FOR RECTAL-CANCER -ITS IMPACT ON STAGE OF DISEASE AND THE ROLE OF ENDORECTAL ULTRASOUND

Background: Preoperative adjuvant radiation combined with chemotherapy is a recent development in the management of patients with rectal can cer invading perirectal tissue and regional lymph nodes. This study wa s performed to assess the impact of preoperative adjuvant therapy in p atients judged by endorectal ultrasound to have extramural invasion of rectal cancer and/or regional lymph node involvement on tumor regress ion in bowel wall and lymph nodes. The predictive value of ultrasound in staging wall penetration and lymph node involvement after preoperat ive adjuvant therapy was also assessed. Methods: Patients (n = 43) wer e selected by ultrasound to have preoperative irradiation (4,500-5,040 cGy over 5-6 weeks). In 30 patients this was combined with 5-fluorour acil, 370 mg/m(2), for 5 days in the first and last weeks of irradiati on. Pretreatment ultrasound was compared with pathologic findings in t he resected specimen in all patients. Twenty-one were assessed by ultr asound after adjuvant therapy and findings compared with histology, Re sults: Downstaging was seen in 23 (53%) patients with wall invasion an d in 23 (72%) of 32 patients with lymph node involvement. Overall, dow nstaging was achieved in 30 (70%), Positive predictive values of ultra sound after irradiation were 72% and 56% for wall penetration and lymp h node status, respectively. Negative predictive values of ultrasound after irradiation were 100% and 82%, respectively. Conclusion: In the majority of patients with rectal cancer invading perirectal tissues or lymph nodes, lesions may be downstaged by preoperative adjuvant thera py. Endorectal ultrasound after adjuvant therapy for rectal cancer is of a lesser predictive value chiefly because of overstaging.