Current and Emerging Treatment Strategies for Anal Cancer

One compared with two cycles of mitomycin C in chemoradiotherapy for anal cancer: analysis of outcomes and toxicity

BACKGROUND

Concurrent chemoradiation with fluorouracil (5fu) and mitomycin C (mmc) is standard treatment for anal canal carcinoma (acc). The current protocol in Alberta is administration of 5fu and mmc during weeks 1 and 5 of radiation. However, administration of the second bolus of mmc has been based largely on centre preference. Given limited published data on outcomes with different mmc regimens, our objective was to compare the efficacy and toxicity of 1 compared with 2 cycles of mmc in acc treatment.

METHODS

Our retrospective study evaluated 169 acc patients treated with radical chemoradiotherapy between 2000 and 2010 at two tertiary cancer centres. All patients were treated with 2 cycles of 5fu and with 1 cycle (mmc1) or 2 cycles (mmc2) of mmc. Acute toxicities, disease-free (dfs) and overall survival (os) were analyzed.

RESULTS

Baseline demographics, performance status, and stage were similar in the groups of patients who received mmc1 (52%) and mmc2 (48%). Before treatment, median hematologic parameters were comparable, except for white blood cell count, which was higher in the mmc2 group, but within normal range. The 5-year os and dfs were similar (75.1% and 54.2% for mmc1 vs. 70.7% and 44.2% for mmc2, p = 0.98 and p = 0.63 respectively). On multivariate analysis, mmc2 was the factor most strongly associated with specific acute toxicities: grade 3+ leukopenia (hazard ratio: 4.82; p < 0.01), grade 3+ skin toxicity (hazard ratio: 4.76; p < 0.001), and hospitalizations secondary to febrile neutropenia (hazard ratio: 9.91; p = 0.001).

CONCLUSIONS

In definitive chemoradiotherapy for acc, 1 cycle of mmc appears to offer outcomes similar to those achieved with 2 cycles, with significantly less acute toxicity.

MRI of anal cancer: assessing response to definitive chemoradiotherapy

Anal cancer is an uncommon malignancy of the gastrointestinal tract but has a relatively good prognosis with an 80% 5-year overall survival. In this article, we review the role of MRI for assessing treatment response in anal cancer after completion of definitive chemoradiotherapy. New generation MRI scanners with optimal-phased array body coils, resulting in better signal to noise and improved contrast and spatial resolution, have contributed to high-resolution imaging in clinical practice enabling visualization of relevant anatomy including the sphincter complex, adjacent structures, mesorectal and pelvic lymph nodes with a diameter down to 2 mm. Multiplanar, high-resolution T2-weighted and diffusion-weighted sequences have a role in initial locoregional staging of anal SCC, assisting radiotherapy planning, as well as in assessing response to treatment and treatment-related complications.

MRI and CT of anal carcinoma: a pictorial review

BACKGROUND

Squamocellular anal carcinoma is increasingly diagnosed in patients with risk factors.

METHODS

State-of-the-art imaging with magnetic resonance imaging (MRI) using phased-array coils and volumetric multidetector computed tomography (CT) provides detailed visualisation of anal disorders, identification and extent assessment of neoplastic tissue, detection and characterisation of nodal and visceral metastases. MRI has been recommended by the European Society for Medical Oncology (ESMO) as the preferred modality of choice to stage anal cancer, taking into account the maximum tumour diameter, invasion of adjacent structures and regional lymph node involvement.

RESULTS

Cross-sectional imaging techniques allow the identification of coexisting complications, and differentiation from other perineal abnormalities.

CONCLUSION

Cross-sectional imaging is useful for planning radiotherapy, surgical drainage or salvage abdomino-perineal resection. After chemo-radiotherapy, MRI follow-up provides confident reassessment of therapeutic response, persistent or recurrent disease. TEACHING POINTS : • Anal carcinoma is increasingly diagnosed in patients with human immunodeficiency virus (HIV), anoreceptive intercourse, chronic inflammatory bowel disease. • An established association exists with human papillomavirus (HPV) infection and premalignant intra-epithelial dysplasia. • Phased-array MRI is recommended as the preferred imaging modality for regional staging. • Imaging allows detection of infectious complications, planning of radiotherapy or salvage surgery. • Follow-up MRI allows reliable assessment of therapeutic response after chemo-radiotherapy.

Squamous cell carcinoma of the anal canal: a review of the aetiology, presentation, staging, prognosis and methods available for treatment

Anal cancer is an uncommon malignancy, with the majority of cases comprised of squamous cell carcinomas. The increasing incidence of this disease reflects a rise in the transmission of the human papillomavirus, the causative organism of most tumours. Abdominoperineal resection (APR), once the primary mode of treatment, has been supplanted by sphincter-saving combination chemoradiation as the first-line therapy. However, surgeons continue to play a role in the multidisciplinary management of patients with anal cancer for diagnosis and post-treatment surveillance. Sentinel node biopsy may identify patients with clinically and radiographically negative inguinal lymph nodes who will benefit from groin irradiation. In very select cases, the controversial means of local excision has been employed as primary treatment, often in conjunction with radiation and chemotherapy. The management of persistent or recurrent anal cancers following primary chemoradiation remains a concern, for which only salvage APR currently offers the possibility of a cure. The introduction of human papillomavirus vaccines presents the exciting potential for the eradication of the disease.

Cost-effectiveness studies in radiation therapy

The field of radiation therapy has made dramatic technical advances over the past 20 years. 3D conformal radiotherapy, intensity-modulated radiation therapy and proton beam therapy have all been developed in an attempt to improve the therapeutic ratio: higher cure rates with lower toxicity. Unfortunately, although the costs of radiation therapy are certainly increasing, it is unclear whether its clinical benefit has also improved. Cost-effectiveness analyses are designed to formally evaluate the cost of a treatment relative to an associated change in quality-adjusted survival. As the cost of oncologic care is increasing, it is critically important to assess the cost-effectiveness of radiation therapy. This article will describe the issues surrounding the delivery and cost of radiation therapy, and it will summarize the work that has been done to evaluate the use of cost-effectiveness in radiation oncology.