Leiomyosarcoma of the rectum and anal canal.

Leiomyosarcoma of the rectum and anal canal is rare and the optimal treatment is not clear. Eight patients with isolated anorectal leiomyosarcoma treated surgically were reviewed. The age ranged from 44 to 76 years (median 63 years) and the follow up ranged from 6 months to 4.5 years (median 2 years). All patients were symptomatic at presentation. All tumours involved the muscularis propria of the low and/or mid-rectum with three tumours also involving the anal sphincters. The tumour size ranged from 1.2 to 10 cm (median 4 cm). Mucosal involvement occurred in only three patients and there was no lymph node involvement. All showed microscopic infiltration at the advancing border, despite macroscopic circumscription. Only one patient was thought to have a tumour sufficiently small (3 cm) and localized on clinical and intrarectal ultrasound examinations (UST2N0) to be suitable for wide local excision. That patient remained tumour-free after 2 years. The remaining patients (88%) were treated by abdomino-perineal resection. The disease free interval in this latter group ranged from 3 months to 4.5 years. All recurrences were detected within 15 months of surgery and the mean interval from detection of recurrence to death was 9 months. Using a histological grading system that included tumour differentiation, mitotic count and amount of necrosis, high grade sarcomas were associated with a worse prognosis. Other factors associated with a poor outcome included large tumour size (> 6-7 cm) and prior incomplete local excision.