Primary treatment of carcinoma of the anus by combined radiotherapy and chemotherapy

Late gastrointestinal toxicity after radiotherapy for anal cancer: a systematic literature review

INTRODUCTION

There is a paucity of data on incidence and mechanisms of long-term gastrointestinal consequences after chemoradiotherapy for anal cancer. Most of the adverse effects reported were based on traditional external beam radiotherapy whilst only short-term follow-ups have been available for intensity-modulated radiotherapy, and there is lack of knowledge about consequences of dose-escalation radiotherapy.

METHOD

A systematic literature review.

RESULTS

Two thousand nine hundred and eighty-five titles (excluding duplicates) were identified through the search; 130 articles were included in this review. The overall incidence of late gastrointestinal toxicity was reported to be 7-64.5%, with Grade 3 and above (classified as severe) up to 33.3%. The most commonly reported late toxicities were fecal incontinence (up to 44%), diarrhea (up to 26.7%), and ulceration (up to 22.6%). Diarrhea, fecal incontinence and buttock pain were associated with lower scores in radiotherapy specific quality of life scales (QLQ-CR29, QLQ-C30, and QLQ-CR38) compared to healthy controls. Intensity-modulated radiation therapy appears to reduce late toxicity.

CONCLUSION

Late gastrointestinal toxicities are common with severe toxicity seen in one-third of the patients. These symptoms significantly impact on patients' quality of life. Prospective studies with control groups are needed to elucidate long-term toxicity.

Squamous cell cancer of the rectum

Squamous cell carcinoma of the rectum is a rare malignancy. It appears to be associated with chronic inflammatory conditions and infections. The clear association seen between Human Papilloma Virus and various squamous cancers has not been firmly established for the squamous cell cancer of the rectum. The presentation is nonspecific and patients tend to present with advanced stage disease. Diagnosis relies on endoscopic examination with biopsy of the lesion. Distinction from squamous cell cancer of the anus can be difficult, but can be facilitated by immunohistochemical staining for cytokeratins. Staging of the cancer with endoscopic ultrasound and computed tomography provides essential information on prognosis and can guide therapy. At present, surgery remains the main therapeutic option; however recent advances have made chemoradiation a valuable therapeutic addition. Squamous cell carcinoma of the rectum is a distinct entity and it is of crucial importance for the practicing Gastroenterologist to be thoroughly familiar with this disease. Compared to adenocarcinoma of the rectum and squamous cell cancer of the anal canal, squamous cell carcinoma of the rectum has different epidemiology, etiology, pathogenesis, and prognosis but, most importantly, requires a different therapeutic approach. This review will examine and summarize the available information regarding this disease from the perspective of the practicing gastroenterologist.

State of the art: gastrointestinal malignancies in the human immunodeficiency virus (HIV) population

The gastrointestinal tract is one of the most common sites for the development of primary neoplasms arising in patients with pre-existing infection with the human immunodeficiency virus (HIV). Over the past decade, new information on the clinical manifestation, natural history, treatment options, and related toxicity have been reported, mostly notably the integration of highly active antiretroviral therapy (HAART). The following is a concise review summarizing the current state-of-the-art for GI tract malignancies in the HIV-positive patient and is designed to assist the clinical oncology team in developing a rationale plan when caring for these patients.

Management of anal canal cancer

PURPOSE

Chemoradiotherapy has replaced radical surgery as the initial treatment of choice for anal canal cancer. The roles of these therapeutic modalities are discussed and recommendations on management of anal canal cancer are made based on currently available evidence. Areas for further studies also are identified.

METHODS

Literature on management of anal canal cancer from January 1970 to July 2003 obtained via MEDLINE was reviewed. Reports on anal margin cancers were excluded.

RESULTS

Randomized, prospective, Phase 3 trials in Europe and the United States showed that chemoradiotherapy with 5-fluorouracil and mitomycin C was superior in local control, colostomy-free rate, progression-free survival, and cancer-specific survival compared with radiation alone. In larger tumors, the addition of mitomycin C to radiotherapy and 5-fluorouracil improves local control, colostomy-free, and disease-free survival but is associated with more acute hematologic toxicity. Chemoradiotherapy, including Cisplatin and 5-fluorouracil, appeared to be equal or superior to surgery as salvage therapy in patients with residual disease six weeks after initial nonsurgical treatment.

CONCLUSIONS

To improve treatment outcomes and reduce treatment-related toxicities, further studies are required to elucidate the optimal drug combination and doses, optimal radiation field, total dose, and fraction sizes. Randomized, multicenter trials are needed to define the treatment protocol that provides the highest rate of sphincter preservation with acceptable toxicity. Few studies addressed the treatment of metastatic disease, which remains a major cause of mortality.

Anal neoplasms

A common theme in most anal neoplasms appears to be a delay in diagnosis due to confusion with more common, benign conditions. Thus, the clinician must maintain a high index of suspicion when evaluating lesions of the anal canal and margin. The use of primary chemoradiation for SCC of the anal canal has resulted in equivalent, if not superior, local control and survival compared with radical surgery, and results in sphincter preservation in over two thirds of cases. Nevertheless, abdominoperineal resection still plays an important role in salvage of treatment failures, and also for patients who are unlikely to tolerate chemoradiation or have pre-existing impaired continence. Recent studies indicate that variations in chemotherapeutic agents and radiation technique might potentially produce even better results. The prognosis for anorectal melanoma, as well as for small cell and undifferentiated tumors, continues to be poor. Fortunately, these are relatively rare tumors.

Carcinoma of the anus: strategies in management

The management of anal cancer underwent an interesting transformation over the last two decades. Prior to this period, the standard definitive treatment for carcinoma of the anal canal was abdominal-perineal resection, which necessitated a permanent colostomy. The organ preservation concept appeared following the discovery of a high complete response rate from preoperative combined chemoradiation prior to abdominal-perineal resection. The organ preservation method of treatment rapidly gained popularity and ultimately saved a large number of patients from undergoing abdominal-perineal resection and colostomy. Chemoradiation treatment itself subsequently went through an evolutionary process. Several studies have sought to define the optimal chemotherapeutic regimen as well as radiation treatment dose and fractionation. Ongoing studies attempt to define an optimal treatment regimen that yields a higher cure rate while minimizing toxicity. We review the etiology, epidemiology, and treatment regimens for anal cancer.

Results of combined modality therapy for patients with anal cancer (E7283). An Eastern Cooperative Oncology Group study

BACKGROUND

This prospective study assessed combined modality therapy of patients with International Union Against Cancer classification T1-4 N0 M0 anal cancer.

METHODS

Protocol therapy consisted of a dose of 4000 cGy to the pelvis, anus, and perineum, followed by a 1000-1300 cGy boost. Infusions of 5-fluorouracil and mitomycin-C were administered when radiation therapy began. A second infusion of 5-fluorouracil was administered 28 days later. Biopsy was performed 6-8 weeks after completion of treatment. Positive biopsy findings resulted in abdominal-perineal resection.

RESULTS

Survival at 7 years for 50 eligible patients was 58%. White patients and those with favorable performance status had significantly better survival. Of the 46 patients evaluable for response, 34 had a complete response, 11 had a partial response, and 1 had no response. Seven-year survival for partial responders was 53%. Freedom from locoregional progression was 80% at 7 years.

CONCLUSION

Treatment with a combination of chemotherapy and radiation therapy is effective for patients with anal cancer. The investigation of methods of improving therapy is warranted.

Recurrent squamous cell carcinoma of the anal canal. Predictors of initial treatment failure and results of salvage therapy

OBJECTIVE

The outcomes of patients with squamous cell carcinoma of the anal canal treated by either sphincter-preserving procedures or radical surgery were evaluated, with the goals of identifying factors predicting treatment failure and quantifying results of salvage therapy in patients with recurrent disease.

BASIC PROCEDURES

A population-based study on all patients in all 159 hospitals of the Department of Veterans Affairs (VA) from 1987 to 1991 was carried out. Data were compiled from several national computerized VA data sets. Supplementary information from local tumor registrars also was obtained, including demographic information, discharge summaries, operative reports, pathology reports, and medical oncology and radiation oncology summaries. From these sources, information on tumor histology, tumor stage, tumor grade, presence of regional or distant metastases, surgical procedures, use of chemotherapy and radiation therapy (RT), toxicity of chemotherapy and RT, development of recurrent disease, treatment of recurrence, survival, and cause of death were obtained.

MAIN FINDINGS

Four hundred five patients with anal cancer were identified by computer search, and 204 (51%) were evaluable; 164 of 204 (80%) had squamous cell carcinoma, 137 of whom (84%) were treated with sphincter-preserving procedures, and 27 of whom (16%) were treated by by radical surgery. One hundred fourteen of 138 (83%) were treated by multimodality therapy, which we defined as local excision followed by chemotherapy and RT. The mean dose of RT among patients treated by multimodality therapy was 4200 +/- 540 cGy and 82% of those treated with multimodality therapy received 5-FU/mitomycin C. Recurrent disease was diagnosed in 43 of all 149 patients (29%) with potentially curable disease. (stages I-III) Multivariate analysis revealed that stage at diagnosis (p = 0.04) and method of treatment (p = 0.03) were the sole predictors of recurrence. Fifty-three percent of patients who underwent salvage abdominoperineal resection (APR) are alive, whereas only 19% who underwent salvage chemotherapy with or without RT are alive.

PRINCIPAL CONCLUSIONS

These data indicate that multimodality therapy currently is being employed in the majority of patients with squamous cell carcinoma of the anal canal in the VA system. Tumor stage and method of treatment appear to affect the likelihood of development of recurrent disease. Salvage APR has curative potential. Results with salvage chemotherapy and RT are disappointing.

Malignant anal tumours

Anal tumours represent 5 per cent of anorectal cancers and exist as two clinical entities: tumours of the anal canal and those of the anal margin. Smoking and sexual behaviour, particularly homosexual anal intercourse, are important aetiological factors. This association is related to anal warts and human papillomavirus infection, notably type 16, which is found in around 70 per cent of warts. Symptoms are non-specific and are frequently attributed to benign conditions. Rectal examination reveals a characteristically infiltrating lesion and any suspicious anal area should be biopsied. There are two histological types. Squamous carcinoma comprises approximately 95 per cent of anal tumours and includes the 35 per cent of tumours derived from the anal transition zone (cloacogenic tumours), containing a mixture of squamous and mucinous elements. The remaining 5 per cent of anal tumours are adenocarcinoma. Squamous cell tumours of the anal canal are probably best treated using radiotherapy (with chemotherapy) as complete response rates, 5-year survival rates, and incidences of normal sphincter function and significant toxicity are around 80, 70, 75 and 20 per cent respectively. Treatment failures may be salvaged by surgery. The 5-year survival and local recurrence rates for radical surgery are around 60 and 25 per cent respectively; there are few indications for local excision. In contrast, 60 per cent of anal margin tumours are suitable for local excision, the 5-year survival rate being in excess of 80 per cent. Combining radiotherapy with surgery may give additional benefit. Current randomized controlled trials should further clarify the relative merits and demerits of the treatment options.

External radiation therapy without chemotherapy in the management of anal cancer

BACKGROUND

Most therapeutic regimens currently in use for sphincter preservation in anal cancer utilize combined radiation therapy and chemotherapy. To provide a basis for comparison with combined therapy results, an analysis was made of patients treated with external radiation therapy without chemotherapy.

METHODS

Eighteen patients with squamous cell, basaloid, or cloacogenic carcinoma of the anal canal were treated with external radiation therapy between January 1, 1980, and December 31, 1989, with the goal of sphincter preservation and cure. Before radiation therapy, five patients had incisional biopsies, two underwent piecemeal removal of the tumor, three had excisional biopsies with positive margins, five had excisional biopsies with negative margins, and three had excisional biopsies with unknown margins. All patients received 45 to 50 Gy in 25 to 28 fractions to the pelvis and perineum, and 16 of the 18 received an additional boost to the primary site to bring the total dose to 55 to 67 Gy in 30 to 38 fractions.

RESULTS

With follow-up of 2.5 to 11.2 years in surviving patients, 5-year projected survival and freedom from local recurrence were 94% and 100%, respectively. Two patients required a temporary colostomy because of treatment complications. No patient required a permanent colostomy or had permanent loss of anal sphincter function as a result of local recurrence or complications.

CONCLUSIONS

These results, combined with others, suggest that external radiation therapy without chemotherapy is an acceptable alternative to combined radiation therapy and chemotherapy in the management of anal cancer.

Diagnosis and treatment of anal carcinoma. An overview

Squamous cell carcinoma of the anal canal gives early symptoms and is easy to diagnose. However, these patients often present with advanced tumours, probably because of patient's and/or doctor's delay. The diagnosis must be confirmed by a conclusive biopsy as the treatment of ano-rectal tumours is based upon correct histopathological diagnosis. Loco-regional tumour control of squamous cell carcinoma is excellent following radiotherapy or combined chemoradiotherapy as only 10-20% of the patients develop a local recurrence. The great majority of these are cured by abdominoperineal resection. However, this treatment involves considerable acute and chronic toxicity, but mortality is less than 2%. There is no general agreement about how to minimize toxicity without hazarding loco-regional tumour control. One way could be to irradiate only the primary tumour site in patients with early lesions, and reserve radiotherapy of regional lymph nodes for more advanced cases. About 20% of the patients develop distant metastases, which make the disease incurable. Hence, frequent, rectal digital examination is the most important follow-up since early local recurrences can easily be cured. There is no general consensus concerning adjuvant chemotherapy, but its potential should be further explored.