Interstitial iridium-192 implantation combined with external radiotherapy in anal cancer: ten years experience

To report our experience in the use of interstitial iridium-192 implantation combined with external radiotherapy in anal cancer.

From 1984 to 1994, 79 patients with anal cancer were treated with radical intent using radiotherapy (plus chemotherapy) at Beatson Oncology Centre, Glasgow, Scotland. The mean and median age at presentation were 68 and 70 years, respectively (range 34-85) with a male-to-female ratio of 0.39. The histologic distribution was as follows: 48 squamous, 16 basaloid, 14 adenocarcinoma, and 1 basal cell carcinoma. The T stages were: 8 T1, 40 T2, 26 T3, and 5 T4 lesions. Twelve (15%) patients had nodal involvement at presentation. All patients underwent interstitial implantation using iridium-192 as part of the initial treatment. Seventy-six patients were treated with external radiotherapy followed by implant with a mean delay of 37 days after the end of radiotherapy. Twelve patients also received chemotherapy with 5-fluorouracil and mitomycin-C concurrently with external radiotherapy. Follow-up ranged from 6 to 123 months, with a median of 37 months.

Seventy-nine patients were analyzed to assess local control, survival, and complications. A complete response rate of 91% (72 of 79) was achieved after planned radiation treatment. At the end of external radiotherapy, 29% (22 of 76) had achieved complete response, 58% (7 of 12) with chemotherapy and 23% (15 of 64) without it. Local control was achieved in 62 of 79 (78%) patients and 8 of 17 (47%) local failures were salvaged by abdominoperineal resection. Five patients developed inguinal node failure; four of these were salvaged. Overall, 10% of all patients developed distant metastasis as the first site of failure and 25% failed at any site after salvage therapy. Time to unsalvageable relapse was significantly different on comparing T stage (p = 0.005) and histology (p = 0.029) of tumor. Major complications requiring surgical intervention were seen in six (7.5%) patients. Anal function preservation with local control was possible in 56 of 79 (71%) patients.

We report excellent results with radiotherapy in T1 and T2 lesions. The role of chemoradiotherapy as radical treatment of anal cancer should be defined in the context of locally advanced tumors.