Radiothérapie des cancers du canal anal

What is the optimal treatment for T1N0 anal squamous cell carcinoma? Analysis of current practices in the prospective French FFCD ANABASE cohort

INTRODUCTION

for localized T1N0 squamous cell carcinoma of the anus (SCCA) standard radiotherapy (RT) may result in overtreatment and alternative strategies are debated.

METHODS

T1N0M0 SCCA treated between 2015 and 2020 by local excision (LE) or RT were analyzed from the French prospective FFCD ANABASE cohort. Treatment strategies, recurrence-free and colostomy-free survivals (RFS, CFS) and prognostic factors were reported.

RESULTS

among 1135 SCCA patients, 99 T1N0M0 were treated by LE(n = 17,17.2%), or RT (n = 82,82.8%) including RT alone (n = 65,79.2%) or chemo-RT (n = 17, 20.7%). Median follow-up was 27.2 months [0.03-54.44]. Median tumor size were 11.4 mm [0.9-20] and 15.3 mm [2-20] in the LE and RT groups respectively. Mean RT tumor dose was 59.4 Gy [18-69.4 Gy]. One patient in LE group and 9 in RT group had a pelvic recurrence, either local (60%), nodal (10%) or both (30%). RFS and CFS at 24 months were 92.2%[95%CI,83.4-96.4] and 94.6%[95%CI,86.1-98.0], at 36 months 88.1%[95%CI,77.1-94.2] and 88.5%[95%CI,77.0-94.5], in LE and RT group respectively, without any significative difference (HR = 0.57;[95%CI,0.07-4.45];p = 0.60). By univariate analysis, male gender was the only prognostic factor(HR = 5.57;95%CI, 1.76-17.63; p = 0.004).

CONCLUSION

this cohort confirms the heterogeneity of T1N0M0 SCCA management, questioning the place of RT alone, reduced dose or RT volume, and the safety of LE.

[Pelvic irradiation and hematopoietic toxicity: A review of the literature]

Pelvic bone marrow is the site of nearly 50% of total hematopoiesis. Radiation therapy of pelvic lymph node areas, and cancers located near the bony structures of the pelvis, exposes to hematological toxicity in the range of 30 to 70%. This toxicity depends on many factors, including the presence or absence of concomitant chemotherapy and its type, the volume of irradiated bone, the received doses, or the initial hematopoietic reserve. Intensity modulated radiation therapy allows the optimisation of dose deposit on at risk organs while providing optimal coverage of target volumes. However, this suggests that dose constraints should be known precisely to limit the incidence of radiation side effects. This literature review focuses firstly on pelvic lymph node areas and bony volumes nearby, then on the effects of irradiation on bone marrow and the current dosimetric constraints resulting from it, and finally on hematological toxicities by carcinologic location and progress in reducing these toxicities.

[Anal canal cancer: In the era of intensity-modulated radiotherapy, outstanding issues]

Intensity-modulated radiotherapy makes possible to optimize the irradiation and spare normal tissues. The toxicity remains important with concomitant chemotherapy often associated. The improvement of MRI and PET-CT define more precisely the target volumes, which need a higher dose, but necessitates to respect the rules of contouring. The treatment is uniform whatever the stage but should be individualized based on clinical stage and tumor response. New paradigms concern biology, staging, volumes and doses, fractionation and combined treatments.

Management of locally advanced anal canal carcinoma with intensity-modulated radiotherapy and concurrent chemotherapy

The best curative option for locally advanced (stages II-III) squamous-cell carcinomas of the anal canal (SCCAC) is concurrent chemo-radiotherapy delivering 36-45 Gy to the prophylactic planning target volume with an additional boost of 14-20 Gy to the gross tumor volume with or without a gap-period between these two sequences. Although 3-dimensional conformal radiotherapy led to suboptimal tumor coverage because of field junctions, this modality remains a standard of care. Recently, intensity-modulated radiotherapy (IMRT) techniques improved tumor coverage while decreasing doses delivered to organs at risk. Sparing healthy tissues results in fewer severe acute toxicities. Consequently, IMRT could potentially avoid a gap-period that may increase the risk of local failure. Furthermore, these modalities reduce severe late toxicities of the gastrointestinal tract as well as better functional conservation of anorectal sphincter. This report aims to critically review contemporary trends in the management of locally advanced SCCAC using IMRT and concurrent chemotherapy.

[Radiotherapy for HIV-infected patients]

Since the advent of highly active antiretroviral therapy, cancer incidence is still 2 to 3-fold higher in patients infected by human immunodeficiency virus (HIV) than in the general population, with an increased incidence of malignancies not associated with acquired immunodeficiency syndrome (AIDS). HIV-infected patients cancer treatment does not differ from that in the general population. However, the management of those patients have some particularities due to preexisting comorbid conditions, including metabolic, cardiovascular, renal or hepatic complications and the risk for potential drug - drug interactions in HIV-infected patients. In this review, we described efficacy and tolerance of radiotherapy with or without chemotherapy in this frail population treated for cancer. Utilization of modern radiotherapy techniques such as intensity-modulated radiotherapy may improve the treatment tolerance.

[Doses to organs at risk for conformational and stereotactic radiotherapy: Bladder]

Bladder dose constraints in case of conformational radiotherapy/intensity-modulated radiotherapy and stereotactic radiotherapy are reported from the literature, in particular from the French radiotherapy society RECORAD recommendations, according to the treated pelvic tumor sites. The dose-volume effect on urinary toxicity is not clearly demonstrated, making difficult to establish absolute dose constraints for the bladder. In case of high-dose prostate cancer radiotherapy, the bladder dose constraints are: V60Gy<50% and maximum dose<80Gy for standard fractionation and V60Gy<5%, V48Gy<25% and V41Gy<50% for moderate hypofractionation (20 fractions of 3Gy). In case of prostate stereotactic radiotherapy (five fractions of 7.25Gy), the most frequent dose constraints in the literature are V37Gy<10cm³ and V18Gy<40%. In case of conformational radiotherapy of cervix cancer, postoperative endometrium, anal canal and rectum, the recommendations are V40Gy<40% and D2% lower than the prescribed dose.

Anal cancer: French Intergroup Clinical Practice Guidelines for diagnosis, treatment and follow-up (SNFGE, FFCD, GERCOR, UNICANCER, SFCD, SFED, SFRO, SNFCP)

INTRODUCTION

This document is a summary of the French Intergroup guidelines regarding the management of anal carcinomas, published in November 2016.

METHODS

It is a collaborative work produced under the auspices of the majority of the French medical societies involved in the management of anal cancer. It is based on the previous guidelines published in 2010. Recommendations are graded in three categories, according to the amount of evidence found in the literature.

RESULTS

Non-metastatic anal carcinomas can be divided into two risk groups, according to magnetic resonance imaging (MRI) or endorectal-ultrasonograpy. Localized small cancers (T1N0) are mainly treated by exclusive radiation therapy in the case of cancers of the anal canal, or by surgery in the case of cancers of the anal margin. The recommended treatment of locally advanced tumours (T2-T4, N0-N2) is definitive concomitant radio-chemotherapy. Salvage surgery should be reserved for patients with poor response, tumour progression or local relapse after radio-chemotherapy, or in cases of persistent vaginal fistula or total anal incontinence after the cessation of radio-chemotherapy. In the case of metastatic tumours, current therapeutic recommendations are based on less robust evidence; with chemotherapy playing a major role.

CONCLUSION

These recommendations are permanently being reviewed, and each individual case must be discussed inside a multidisciplinary team.