Anorectal location of melanomas is rare and agressive. The discovery that the KIT oncogene may be aberrantly activated in a subset of patients creates a realm of possibility for the development of targeted molecular therapy. The aim is to show the epidemiologic, clinico-radiological, histological features and treatment management especially in patients with over-expression of CKIT treated by Imatinib.
Retrospective study conducted in medical oncology department at Hassan II University Hospital, Fez, Morocco, between January 2007 and January 2014, including patients with anorectal melanoma. CKIT Assessment was performed in all patients.
Twenty patients were collected, 11 men and 9 women, the mean age was 57 years (45-81ans). The symptoms were mainly rectal bleeding, proctalgia, rectal syndrome, and transit disorders. Colonoscopy was performed in all cases and revealed a circumferential non-pigmented burgeoning tumor in all cases and stenotic tumor in 17 cases. The radiological assessment included a thoraco-abdomino-pelvic scan in all cases and 13 patients underwent a pelvic MRI.
Seventeen patients had a metastatic disease at the diagnosis, sites of metastases were: liver, lymph node and lung. Only three patients were not metastatic, and proceeded to surgery, they underwent an abdomino-perineal resection with lymphadenectomy; but the evolution was marked by occurrence of pulmonary and hepatic metastases less than 12 months later.
First-line chemotherapy was received in all patients; it was based mainly on paclitaxel, carboplatine and dacarbazine, with only 5 partial responses, 6 disease stabilities, and 9 patients with disease progression. Five patients had over-expression of CKIT and they received Imatinib as second line of treatment with significant improvement of symptoms and significant radiological response in all patients reaching 60%. Their median survival was 14,3 months vs 10 months for patients without CKIT overexpression.
Anorectal melanoma is an agressive rare cancer.The prognosis remains poor for metastatic stage despite the systemic therapy. Treatment is still big challenge. Results of targeting CKIT with Imatinib were very hopeful and encouraging to develop new targets.
Clinical trial identification
All authors have declared no conflicts of interest.