Primary colorectal lymphomas.

OBJECTIVE: The incidence of primary colorectal lymphomas is rare, comprising 10-20% of gastrointestinal lymphomas and only 0.2-0.6% of large bowel malignancies. There is a male predominance, with a maximal reported incidence in the 50- to 70-year age group. Patients often present delayed with nonspecific symptoms and consequently have advanced disease at the time of diagnosis. Inflammatory bowel disease and immunosuppression have been reported as risk factors, although a direct causal link has yet to be established. Treatment often involves a multimodality approach, combining surgery and chemotherapy, with the use of radiotherapy in selected cases. We present our experience in the management of primary colorectal lymphomas over a 10-year period (1989-1999). PATIENTS AND METHODS: We reviewed all cases of primary colorectal lymphoma seen at our institution from 1989 to 1999. Patients were included based on standard diagnostic criteria for primary intestinal lymphoma established by Dawson in 1961. The following clinical information was obtained: age, sex, presentation, site of tumour, operation performed, histology, length of stay, intraoperative complications, adjuvant therapy and duration of follow-up. The type of lymphoma was classified according to the WHO classification system. For staging, a modification of the Ann Arbor system for gastrointestinal lymphoma, proposed by Musshoff, was used.
RESULTS: During the 10-year period from 1989 to 1999, 14 cases of primary colorectal lymphomas were identified. This comprised 0.44% of all colorectal malignancies (14 of 3199 cases) seen in our department during this period. There were 13 men and one woman. Their mean age at presentation was 61 years. The common presentations included a combination of abdominal pain (71.4%), anorexia and loss of weight (42.9%) and an abdominal mass (28.6%). The two most common sites of involvement were the caecum (57.1%) and the rectum/sigmoid colon (21.4%). The lesions manifested in a variety of ways, ranging from solitary fungating masses to multiple colonic polyps. All but one patient underwent attempted curative surgical resection. All cases were non-Hodgkin's B-cell lymphomas, with a majority being diffuse large B-cell lymphomas (57.1%). The diagnoses were established through laparotomy in all cases. All cases presented with evidence of spread to regional lymph nodes or beyond. Eleven patients (78.6%) received postoperative chemotherapy, with a regimen that included cyclophosphamide, vincristine, doxorubicin and prednisone. The remaining three were too ill or refused. There were no mortalities within 30 days of surgery. The patients were followed up for a median of 20 months (range 2-84) and more than half are alive and continue to be on follow-up with no evidence of recurrence.
CONCLUSION: Primary colorectal lymphoma is a rare condition. It predominantly affects males between the sixth and seventh decade of life and most commonly occurs in the caecum. It often presents with abdominal pain and loss of weight and due to the nonspecific nature of these symptoms, patients frequently present late with advanced loco-regional disease. The histology is usually B cell and of intermediate grade. Therapy usually involves resection of the affected colon and regional lymphovascular structures, followed by adjuvant chemotherapy, with a reported 5-year survival of 27-55%.