The patient received chemotherapy and local radiotherapy as a result of aggressive tumor behavior. The treatment consisted of 4 cycles of cyclophosphamide, hydroxydaunomycin, vincristine, prednisone, and rituximab, followed by radiotherapy. The remaining chemotherapy cycles were given at the end of radiotherapy. After completing treatment for lymphoma, adjuvant chemotherapy with 5-fluorouracil, leucovorin, and oxaplatin (FOLFOX) for CRC was also administered. Following aggressive medical and surgical management, the patient survived 30 months after diagnosis.
Colliding lesions of colonic lymphoma and CRC are rare. Adenocarcinoma is the most common colonic malignancy but only presents with synchronous or metachronous tumors in 5% of cases.5,6 In contrast, colorectal lymphoma is extremely infrequent, representing <0.5% of all primary CRC.4 The clinical presentation of collision tumors is not specific and depends primarily on the affected organ. Our patient presented with symptomatic anemia without evidence of bleeding, which led us to perform a diagnostic colonoscopy.
The evolution of collision tumors is intriguing in terms of carcinogenesis of malignant lymphoma and progression to carcinoma.5 One hypothesis suggests that tumors arise in continuity through an accidental event and that the presence of one tumor precipitates the adjacent tumor by altering the microenvironment.4,6 A lymphomatous process may be the initial event, compromising the patient's immune system.4 Nonetheless, there is no evidence that immunodeficiency induces activation of oncogenes or inactivation of tumor-suppressor genes.5 In our case, ulcerative colitis could have been the precipitating factor that led to dysplastic changes evolving into malignancy.
Optimal management of GI lymphomas is the subject of debate and has not been studied in randomized trials.4 In cases of collision tumors, the influence of one malignancy on the behavior of the other greatly increases the complexity of treatment.1 Our approach consisted of surgical resection followed by directed chemotherapy and radiotherapy, and finally chemotherapy for CRC. This case accentuates how the choice of treatment invariably depends on the patient's age and performance status, clinical scenario, histological subtype, and extent of disease.
Little is known regarding colorectal lymphomas in minority groups or its association with CRC.7 Studies have demonstrated that, in Hispanics, CRC is diagnosed at an earlier age and with a more advanced stage, and it tends to have a more aggressive course.7 Studies regarding incidence, prevalence, and epidemiology of collision tumors and their clinical presentation and response to treatment are needed.
Author contributions: All authors wrote and edited the manuscript. DH Toro is the article guarantor.
Financial disclosure: None to report.
Informed consent was obtained for this case report.
Received June 2, 2017; Accepted December 12, 2017
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© 2018 by Lippincott Williams & Wilkins, Inc.
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