External beam radiotherapy ± chemotherapy in the treatment of anal canal cancer: a single-institute long-term experience on 100 patients

Modern intensity-modulated radiotherapy with image guidance allows low toxicity rates and good local control in chemoradiotherapy for anal cancer patients

PURPOSE

To report outcomes of a population of anal cancer patients treated with modern intensity-modulated radiotherapy and daily image-guided radiotherapy techniques.

METHODS

We analyzed data of 155 patients consecutively treated with intensity-modulated radiotherapy +/- chemotherapy in three radiotherapy departments. One hundred twenty-two patients presented a stage II-IIIA disease. Chemotherapy was administered in 138 patients, mainly using mitomycin C and 5-fluorouracil (n = 81). All patients received 36 Gy (1.8 Gy/fraction) on the pelvic and inguinal nodes, on the rectum, on the mesorectum and on the anal canal, and a sequential boost up to a total dose of 59.4 Gy (1.8 Gy/fraction) on the anal canal and on the nodal gross tumor volumes.

RESULTS

Median follow-up was 38 months (interquartile range 12-51). Toxicity data were available for 143 patients: 22% of them presented a G3+ acute toxicity, mainly as moist desquamation (n = 25 patients) or diarrhea (n = 10). Three patients presented a late grade 3 gastrointestinal toxicity (anal incontinence). No grade 4 acute or late toxicity was recorded. Patients treated with fixed-gantry IMRT delivered with a sliding window technique presented a significantly higher risk of acute grade 3 (or more) toxicity compared to those treated with VMAT or helical tomotherapy (38.5 vs 15.3%, p = 0.049). Actuarial 4-year local control rate was 82% (95% CI 76-91%).

CONCLUSIONS

Modern intensity-modulated radiotherapy with daily image-guided radiotherapy is effective and safe in treating anal cancer patients and should be considered the standard of care in this clinical setting.

Nodal stage migration and prognosis in anal cancer: a systematic review, meta-regression, and simulation study

BACKGROUND

In patients with squamous cell carcinoma of the anus (SCCA), lymph node positivity (LNP) indicates poor prognosis for survival and is central to radiotherapy planning. Over the past three decades, LNP proportion has increased, mainly reflecting enhanced detection with newer imaging modalities; a process known as nodal stage migration. If accompanied by constant T stage distributions, prognosis for both lymph node-positive and lymph node-negative groups may improve without any increase in overall survival for individual patients; a paradox termed the Will Rogers phenomenon. Here, we aim to systematically evaluate the impact of nodal stage migration on survival in SCCA and address a novel hypothesis that this phenomenon results in reduced prognostic discrimination.

METHODS

We did a systematic review and meta-regression to quantify changes in LNP over time and the impact of this change on survival and prognostic discrimination. We searched MEDLINE, Embase, and the Cochrane Library to identify randomised trials and observational studies in patients with SCCA published between Jan 1, 1970, and Oct 11, 2016. Studies were eligible if patients received chemoradiotherapy or radiotherapy as the main treatment, reported LNP proportions (all studies), and reported overall survival (not necessarily present in all studies). We excluded studies with fewer than 50 patients. We extracted study-level data with a standardised, piloted form. The primary outcome measure was 5-year overall survival. To investigate scenarios in which reduced prognostic discrimination might occur, we simulated varying true LNP proportions and true overall survival, and compared these with expected observed outcomes for varying levels of misclassification of true nodal state.

FINDINGS

We identified 62 studies reporting LNP proportions, which included 10 569 patients. From these, we included 45 studies (6302 patients) with whole cohort 5-year overall survival, 11 studies with 5-year survival stratified by nodal status, and 20 studies with hazard ratios in our analyses of temporal changes. In 62 studies, the LNP proportions increased from a mean estimate of 15·3% (95% CI 10·5-20·1) in 1980 to 37·1% (34·0-41·3) in 2012 (p<0·0001). In 11 studies with prognostic data, increasing LNP was associated with improved overall survival in both lymph node-positive and lymph node-negative categories, whereas the proportions with combined tumour stage T3 and T4 remained constant. In 20 studies, across a range of LNP proportions from 15% to 40%, the hazard ratios for overall survival of lymph node-positive versus lymph node-negative patients decreased significantly from 2·5 (95% CI 1·8-3·3) at 15% LNP to 1·3 (1·2-1·9; p=0·014) at 40% LNP. The simulated scenarios reproduced this effect if the true LNP proportions were 20% or 25%, but not if the true LNP proportions were 30% or greater.

INTERPRETATION

We describe a consequence of staging misclassification in anal cancer that we have termed reduced prognostic discrimination. We used this new observation to infer that the LNP proportions of more than 30% seen in modern clinical series (11 out of 15 studies with a median year since 2007) are higher than the true LNP proportion. The introduction of new staging technologies in oncology might misclassify true disease stage, spuriously informing disease management and ultimately increasing the risk of overtreatment.

FUNDING

Bowel Disease Research Foundation.

Intensity-modulated radiation therapy with simultaneous integrated boost combined with concurrent chemotherapy for the treatment of anal cancer patients: 4-year results of a consecutive case series

PURPOSE

To report the 4-year outcomes of a consecutive series of anal cancer patients treated with concurrent chemo-radiation delivered with intensity-modulated radiotherapy (IMRT), employing a simultaneous integrated boost (SIB) approach.

METHODS

A consecutive series of 54 patients was enrolled between 2007 and 2013. Treatment schedule consisted of 50.4 Gy/28 fractions (1.8 Gy daily) to the gross tumor volume, while the elective nodal volumes were prescribed 42 Gy/28 fractions (1.5 Gy/daily) for patients having a cT2N0 disease. Patients with cT3-T4/N0-N3 tumors were prescribed 54 (T3) or 60 (T4) Gy/30 fractions (1.8-2 Gy daily) to the gross tumor volume; gross nodal volumes were prescribed 50.4 Gy/30 fr (1.68 Gy daily) if sized ≤ 3 cm or 54 Gy/30 fr (1.8 Gy daily) if > 3 cm; elective nodal regions were given 45 Gy/30 fractions (1.5 Gy daily). Chemotherapy was administered concurrently according to the Nigro's regimen. Primary endpoint was colostomy-free survival (CFS). Secondary endpoints were local control (LC), disease-free survival (DFS), cancer-specific survival (CSS), overall survival (OS), and toxicity profile.

RESULTS

Median follow up was 32.6 months (range 12-84). The actuarial probability of being alive at 4 years without a colostomy (CFS) was 68.9% (95% CI: 50.3%-84.7%). Actuarial 4-year OS, CSS, DFS, and LC were 77.7% (95% CI: 60.7-88.1%), 81.5% (95% CI: 64%-91%), 65.5% (95% CI: 47.7%-78.5%), and 84.6% (95% CI: 71.6%-92%). Actuarial 4-year metastasis-free survival was 74.4% (95% CI: 55.5%-86.2%). Maximum detected acute toxicities were as follows: dermatologic -G3: 13%; GI-G3: 8%; GU-G3: 2%; anemia-G3: 2%; neutropenia-G3:11%; G4: 2%; thrombocytopenia- G3:2%. Four-year G2 chronic toxicity rates were 2.5% (95% CI: 3.6-16.4) for GU, 14.4% (95% CI: 7.1-28) for GI, 3.9% (95% CI: 1%-14.5%) for skin, and 4.2% (95% CI: 1.1-15.9) for genitalia.

CONCLUSIONS

Our study shows the feasibility of IMRT in the combined modality treatment of anal cancer, with comparable results to the literature with respect to LC, sphincter preservation and survival. Acute toxicity is lower if compared to series employing standard techniques. Our results support the use of IMRT on a routine basis for the treatment of anal cancer.

Anal cancer treatment: Current status and future perspectives

Anal cancers (AC) are relatively rare tumors. Their incidence is increasing, particularly among men who have sex with other men due to widespread infection by human papilloma virus. The majority of anal cancers are squamous cell carcinomas, and they are treated according to stage. In local and locally advanced AC, concomitant chemoradiation therapy based on mitomycin C and 5-Fluorouracil (5-FU) is the current best treatment, while metastatic AC, chemotherapy with 5-FU and cisplatin remains the gold standard. There are no indications for induction or maintenance therapies in locally advanced tumors. Many novel strategies, such as targeted therapies, vaccination, immunotherapy and photodynamic therapy are in clinical trials for the treatment of AC, with promising results in some indications.