Metastatic small cell rectal cancer – A rare case of malignancy, as a challange for the clinician

A 54-old patient was operated on in a secondary center with rectal neuroendocrine adenocarcinoma NSE and cgA positive (pT3 pN2/5/10/M0) two years ago. After the operation the patient was treated with 5 cycles of 5FU-LV adjuvant chemotherapy.

Multiple liver metastasis and local recidive was found on an early CT staging wich was made for pelvic pain. An ectopic, presacral left kidney was also observed on this CT scan.

Than the patient was reffered to our department because of progressive disease. The histological revision of the original tumour revealed not a neuroendocrine nor a typical adenocarcinoma, but a small cell rectal cancer. This tumor type is very rare (<1% colorectal cancer) and similar in morphology, immunphenotype and behavior to small cell carcinoma of the lung and highly agressive with 70% having liver metastasis at the time of diagnosis. The thoracic CT was negative. According to the new pathological findings, a cisplatine-vepeside chemotherapy was given, but it had to be finished after 7 cycles because of nephrotoxicity and complete remission on the PET-CT scan. Pelvic radiotherapy was planned too, but the ectopic left kidney (witch was responsible about 80% of the total amount of filtration, according to the camera-renography) could not be saved even with CT-based, 3 dimensional IMRT technique. According to our small cell pulmonary tumour protocol, a preventive whole brain irradiation (15×2Gy) was also performed.

After two-year follow-up the patient's disease is in complete remission.

Our case report highlights the importance of precise histology of the rare cases of the unusual colorectal cancers.