Surgery of anal cancer
Primary surgery may be relevant for small perianal cancers (< 1 cm). Sigmoidostomy may have to be performed before start of radiation treatment for defecation problems, obstruction, incontinence or fistula.
Local treatment failure (remaining cancer or local recurrence)
Local treatment failure includes both cancer remaining after chemoradiotherapy, progression of tumor in spite of chemoradiotherapy, or later local recurrence. There is no reason for differentiating the various malignant conditions with regard to surgical intervention.
A local ulceration remaining after radiotherapy leaves suspicion of persistent cancer and must be biopsied. There is much evidence suggesting that active follow up will increase the percentage of early diagnoses of local treatment failure, thereby increasing the frequency of radical salvage operations. Local treatment failure is usually given as 20-25% within a three year period.
Patients with local treatment failure shall be considered for salvage surgery with abdomino perineal resection (rectal amputation). The tumor should be biopsied and the patient evaluated for operability and resectability. MRI of the pelvis should be performed and distant metastases must be excluded by CT and PET scan. For operable metastases in the groins salvage surgery may be an option. For other distant metastases surgery may be considered in special cases, but the effect of this is not documented.
A few patients may be treated by local resection of the recurrence, especially if the tumor is located in the soft tissue and is mobile. This, however, is rarely the case. Recurrence of small perianal cancers that previously have been locally resected may be re-resected with wide margins.
Radical salvage surgery
Radical or extended rectal amputation (APR) is indicated if the cancer is not confined within the intestinal tube or anal verge. The tumor tends to grow circularly into the surrounding tissues leaving the margins towards the surrounding organs or structures threatened or invaded. Such extended operations should be performed as en-bloc resection where free margins of all cancer tissue is the goal. Tissue with post-irradiation scarring and fibrotic tissue should be resected. Wide resections of the perineum and often the muscles of the pelvic floor as well as resections of the posterior vaginal wall will often have to be performed. The perianal skin must also be widely resected. The perineal resection must often be more extensive than in operations for rectal cancer. For posteriorly growing tumors the coccygus or distal sacrum may have to be removed as part of the en-bloc resection. It has been shown to be advantageous to stop the abdominal resection earlier and continue in a plan outside the pelvic floor from the perineal side. An extended symmetrical specimen may then be obtained. Such extended operations should always be performed in large lowlying tumors (T3/T4). Delayed healing of the perineum is commonly seen when primary closure is performed. (40-70%).
Reconstruction by plastic surgery
Salvage surgery leaves a large defect in the perineum, pelvic floor and cavity. To cover the defect, improve the healing and reduce the danger of pelvic abscesses, reconstruction by plastic surgery is often part of the surgical procedure. Application of flaps may reduce the healing problems down to 15%. Mobilization of the omentum into the pelvis may be advantageous.
Dissection of inguinal lymph nodes
For simultaneous inguinal lymph node metastases a formal lymph node dissection should be performed in combination with the pelvic surgery. This should also be done for isolated inguinal lymph node manifestations.
Prognosis after salvage surgery
Salvage surgery can give patient with local treatment failure a chance of freedom for cancer. Positive resection margin is the strongest negative predictor for survival after the salvage surgery. It is customary to estimate a local cancer control of 50-60% and a 5-year survival of 40-46% after salvage surgery.
Local recurrence of cancer in the anal canal is a rare condition. The combination of surgical challenges with extensive surgery and the required cooperation with other surgical specialties (urology, plastic surgery) suggests that salvage surgery for local treatment failure of anal cancer should be centralized in Norway.
Surgery for metastases
There are no large studies on the effect of surgery for distant metastases from anal cancer. Surgery for metastases in inguinal lymph nodes may be relevant when local chemoradiotherapy has failed. For few or single metastases in the follow up period surgery may be considered. Advanced liver- and lung- surgery has not been evaluated with regard to survival.
Symptomatic tumors, as for instance from the vertebral column, other parts of the skeleton and CNS, may be considered for palliative surgery. Sigmoidostomy may be appropriate for locally inoperable tumor or recurrence.