Intensity-modulated radiation therapy of anal squamous cell carcinoma: Relationship between delineation quality and regional recurrence

Tumor Dormancy and Reactivation: The Role of Heat Shock Proteins

Tumors are a heterogeneous group of cell masses originating in various organs or tissues. The cellular composition of the tumor cell mass interacts in an intricate manner, influenced by humoral, genetic, molecular, and tumor microenvironment cues that dictate tumor growth or suppression. As a result, tumors undergo a period of a dormant state before their clinically discernible stage, which surpasses the clinical dormancy threshold. Moreover, as a genetically imprinted strategy, early-seeder cells, a distinct population of tumor cells, break off to dock nearby or extravasate into blood vessels to secondary tissues, where they form disseminated solitary dormant tumor cells with reversible capacity. Among the various mechanisms underlying the dormant tumor mass and dormant tumor cell formation, heat shock proteins (HSPs) might play one of the most important roles in how the dormancy program plays out. It is known that numerous aberrant cellular processes, such as malignant transformation, cancer cell stemness, tumor invasion, metastasis, angiogenesis, and signaling pathway maintenance, are influenced by the HSPs. An accumulating body of knowledge suggests that HSPs may be involved in the angiogenic switch, immune editing, and extracellular matrix (ECM) remodeling cascades, crucial genetically imprinted strategies important to the tumor dormancy initiation and dormancy maintenance program. In this review, we highlight the biological events that orchestrate the dormancy state and the body of work that has been conducted on the dynamics of HSPs in a tumor mass, as well as tumor cell dormancy and reactivation. Additionally, we propose a conceptual framework that could possibly underlie dormant tumor reactivation in metastatic relapse.

Nordic anal cancer (NOAC) group consensus guidelines for risk-adapted delineation of the elective clinical target volume in anal cancer

Background: To date, anal cancer patients are treated with radiotherapy to similar volumes despite a marked difference in risk profile based on tumor location and stage. A more individualized approach to delineation of the elective clinical target volume (CTVe) could potentially provide better oncological outcomes as well as improved quality of life. The aim of the present work was to establish Nordic Anal Cancer (NOAC) group guidelines for delineation of the CTVe in anal cancer.Methods: First, 12 radiation oncologists reviewed the literature in one of the following four areas: (1) previous delineation guidelines; (2) patterns of recurrence; (3) anatomical studies; (4) common iliac and para-aortic recurrences and delineation guidelines. Second, areas of controversy were identified and discussed with the aim of reaching consensus.Results: We present consensus-based recommendations for CTVe delineation in anal cancer regarding (a) which regions to include, and (b) how the regions should be delineated. Some of our recommendations deviate from current international guidelines. For instance, the posterolateral part of the inguinal region is excluded, decreasing the volume of irradiated normal tissue. For the external iliac region and the cranial border of the CTVe, we agreed on specifying two different recommendations, both considered acceptable. One of these recommendations is novel and risk-adapted; the external iliac region is omitted for low-risk patients, and several different cranial borders are used depending on the individual level of risk.Conclusion: We present NOAC consensus guidelines for delineation of the CTVe in anal cancer, including a risk-adapted strategy.

Estimated dose to site of loco-regional recurrence after radiotherapy in anal cancer using point of origin methods

Background and purpose

Loco-regional recurrence (LRR) dominates the failure pattern after curative radiotherapy in anal cancer. The aim of this study was to estimate dose of LRRs in anal cancer using a point of origin-based method.

Method and materials

Of 321 patients with squamous cell carcinoma of the anus, 31 patients with LRR (29 local recurrences and 5 regional lymph node recurrences) were available for analysis. The recurrence volumes were delineated on recurrence magnetic resonance imaging (rMRI). Rigid and subsequent deformable co-registration of planning computerised tomography scans and rMRI were performed. Point of origin was estimated as the centre of mass (COM) and an observer-based point of origin (obs-PO). Doses to COM and obs-PO, as well as the full recurrence volume, were estimated and the relation to target volumes was extracted.

Results

The median minimum dose to COM was 63.8 Gy (range 32.5-65.1 Gy) and 63.7 Gy (range 35.5-65.2 Gy) to obs-PO of local recurrences. COM was included in the high dose volume (64 Gy) in 86 % of cases, and obs-PO was included in 75 % of cases. There was no difference in minimum dose to COM and obs-PO, and the median distance between the two points was 3.3 mm (range 0.6-19.8 mm). No recurrences occurred in primarily boosted lymph nodes.

Conclusion

The majority of LLRs were located within the high dose volume indicating radioresistance as the primary cause of recurrence in anal cancer. No difference between the use of COM and obs-PO was evident.

ECOG-ACRIN Guideline for Contouring and Treatment of Early Stage Anal Cancer Using IMRT/IGRT

PURPOSE

Previous anal cancer guidelines delineate target volumes similarly for all patients with squamous cell carcinoma of the anal canal and/or perianal skin (SCCA), regardless of disease stage. The purpose of this guideline is to provide customized radiation treatment recommendations for early stage (T1-2 N0 M0) anal cancer treated with intensity modulated and image guided radiation therapy (RT).

METHODS AND MATERIALS

A contouring atlas and radiation treatment recommendations for the ongoing, randomized phase II trial of deintensified chemoradiation for early stage SCCA (EA2182) was created by an expert panel of radiation oncologists. A literature search was conducted to update and expand these recommendations into a guideline for routine clinical use.

RESULTS

For the majority of cases, we recommend treatment in the supine, frog leg position with the use of a customized immobilization device and daily image guided RT to ensure optimal bone and soft tissue alignment. Vaginal dilators can be used daily during RT to maximize genitalia sparing. We recommend use of a 10-mm margin on the gross tumor plus including the anal complex to create the primary clinical target volume. To define the elective lymph node clinical target volume, we recommend starting with a 7-mm expansion on blood vessels, but then further refining these volumes based on the anatomic location. A 5- to 10-mm planning target volume (PTV) margin is suggested based on institutional setup and patient-specific factors. When using a simultaneous integrated boost technique, a dose of 50.4 Gy to primary PTV and 42 Gy to lymph node PTV, both delivered over 28 fractions, with chemotherapy is appropriate for early stage anal cancer.

CONCLUSIONS

This guideline provides anatomic, clinical, and technical instructions to guide radiation oncologists in the planning and delivery of intensity modulated and image guided RT for early stage SCCA.

Prognostic factors for patients with anal cancer treated with conformal radiotherapy-a systematic review

AIMS

Anal cancer is primarily treated using concurrent chemoradiotherapy (CRT), with conformal techniques such as intensity modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) now being the standard techniques utilised across the world. Despite this, there is still very limited consensus on prognostic factors for outcome following conformal CRT. This systematic review aims to evaluate the existing literature to identify prognostic factors for a variety of oncological outcomes in anal cancer, focusing on patients treated with curative intent using contemporary conformal radiotherapy techniques.

MATERIALS AND METHODS

A literature search was conducted using Medline and Embase to identify studies reporting on prognostic factors for survival and cancer-related outcomes after conformal CRT for anal cancer. The prognostic factors which were identified as significant in univariable and multivariable analysis, along with their respective factor effects (where available) were extracted. Only factors reported as prognostic in more than one study were included in the final results.

RESULTS

The results from 19 studies were analysed. In both univariable and multivariable analysis, N stage, T stage, and sex were found to be the most prevalent and reliable clinical prognostic factors for the majority of outcomes explored. Only a few biomarkers have been identified as prognostic by more than one study - pre-treatment biopsy HPV load, as well as the presence of leukocytosis, neutrophilia and anaemia at baseline measurement. The results also highlight the lack of studies with large cohorts exploring the prognostic significance of imaging factors.

CONCLUSION

Establishing a set of prognostic and potentially predictive factors for anal cancer outcomes can guide the risk stratification of patients, aiding the design of future clinical trials. Such trials will in turn provide us with greater insight into how to effectively treat this disease using a more personalised approach.

Long-Term Outcomes of NRG Oncology/RTOG 0529: A Phase 2 Evaluation of Dose-Painted Intensity Modulated Radiation Therapy in Combination With 5-Fluorouracil and Mitomycin-C for the Reduction of Acute Morbidity in Anal Canal Cancer

PURPOSE

A multi-institutional phase 2 trial assessed long-term outcomes of dose-painted intensity modulated radiation therapy (IMRT) with 5-fluorouracil (5FU) and mitomycin-C (MMC) for anal canal cancer.

METHODS AND MATERIALS

T2-4N0-3M0 anal cancers received 5FU (1000 mg/m²/d, 96-hour infusion) and MMC (10 mg/m² bolus) on days 1 and 29 of dose-painted IMRT prescribed as follows: T2N0 = 42 Gy elective nodal and 50.4 Gy anal tumor planning target volumes, 28 fractions; T3-4N0-3 = 45Gy elective nodal, 50.4 Gy ≤3 cm and 54 Gy >3cm metastatic nodal and 54 Gy anal tumor planning target volumes, 30 fractions. Local-regional failures, distant metastases, and colostomy failures were assessed using the cumulative incidence method, and disease-free survival, overall survival, and colostomy-free survival were assessed using the Kaplan-Meier method. Late effects were scored using National Cancer Institute-Common Terminology Criteria for Adverse Events v3.

RESULTS

Of 52 patients, 54% were stage II, 25% were stage IIIA, and 21% were stage IIIB. Median follow-up was 7.9 years (min-max, 0.02-9.2 years). Local-regional failure, colostomy failures, distant metastases, overall survival, disease-free survival, and colostomy-free survival at 5 years are 16% (95% confidence interval [CI], 7%-27%), 10% (95% CI, 4%-20%), 16% (95% CI, 7%-27%), 76% (95% CI, 61%-86%), 70% (95% CI, 56%-81%), and 74% (95% CI, 59%-84%); and at 8 years they are 16% (95% CI, 7%-27%), 12% (95% CI, 5%-23%), 22% (95% CI, 12%-34%), 68% (95% CI, 53%-79%), 62% (95% CI, 47%-74%) and 66% (95% CI, 51%-77%), respectively. Eight patients experienced local-regional failure, with 5 patients having persistent disease at 12 weeks. No isolated nodal failures occurred in the microscopic elective nodal volumes. Six patients required colostomy-5 for local-regional salvage and 1 for a temporary ostomy for anorectal dysfunction. Rates of late adverse events included: 28 patients (55%) with grade 2, 8 patients (16%) with grade 3, 0 patients with grade 4, and 2 patients (4%) with grade 5 events (sinus bradycardia and myelodysplasia, possibly owing to chemotherapy). Only 11 patients reported grade 1 to 3 sexual dysfunction.

CONCLUSIONS

Dose-painted IMRT with 5FU/MMC for the treatment of anal canal cancer yields comparable long-term efficacy as conventional radiation cohorts. Enhanced normal tissue protection lowered rates of grade 3 and higher late effects without compromising pelvic tumor control.

Treatment outcomes and prognostic factors after chemoradiotherapy for anal cancer

BACKGROUND

Squamous cell carcinoma of the anus (SCCA) is a rare malignancy with rising incidence, associated with human papilloma virus (HPV). Chemoradiotherapy (CRT) is the preferred treatment. The purpose was to investigate treatment failure, survival and prognostic factors after CRT.

MATERIAL AND METHODS

In this prospective observational study from a large regional centre, 141 patients were included from 2013 to 2017, and 132 were eligible for analysis. The main inclusion criteria were SCCA, planned radiotherapy, and performance status (ECOG) ≤2. Patient characteristics, disease stage, treatment, and treatment response were prospectively registered. Disease-free survival (DFS), overall survival (OS), and locoregional treatment failure after CRT were analysed. Hazard ratios (HRs) were estimated with Cox`s proportional hazards model.

RESULTS

Median follow-up was 54 (range 6-71) months. Eighteen patients (14%) had treatment failures after CRT; of these 10 (8%) had residual tumour, and 8 (6%) relapse as first failure. The first treatment failure was locoregional (11 patients), distant (5 patients), and both (2 patients). Salvage abdomino-perineal resection was performed in 10 patients, 2 had resections of metastases, and 3 both. DFS was 85% at 3 years and 78% at 5 years. OS was 93% at 3 years and 86% at 5 years. In analyses adjusted for age and gender, HPV negative tumours (HR 2.5, p = 0.024), N3 disease (HR 2.6, p = 0.024), and tumour size ≥4 cm (HR 2.4, p = 0.038) were negative prognostic factors for DFS.

CONCLUSION

State-of-the-art chemoradiotherapy for SCCA resulted in excellent outcomes, and improved survival compared with previous national data, with <15% treatment failures and a 3-year DFS of >80%.

Patterns of recurrence in anal cancer: a detailed analysis

Background

Anal cancer is a rare disease, which might be the reason for the “one size fits all” approach still used for radiotherapy target contouring. To refine and individualize future guidelines, detailed and contemporary pattern of recurrence studies are needed.

Methods

Consecutive anal cancer patients, all treated with curative intent intensity-modulated radiotherapy (IMRT), were retrospectively studied (n = 170). Data was extracted from medical records and radiological images. Radiotherapy planning CT’s and treatment plans were reviewed, and recurrences were mapped and categorized according to radiation dose.

Results

The mean dose to the primary tumor was 59.0 Gy. With a median follow-up of 50 months (range 14–117 months), 5-year anal cancer specific survival was 86.1%. Only 1 of 20 local recurrences was located outside the high dose (CTVT) volume. More patients experienced a distant recurrence (n = 34; 20.0%) than a locoregional recurrence (n = 24; 14.1%). Seven patients (4.2%) had a common iliac and/or para-aortic (CI/PA) recurrence. External iliac lymph node involvement (P = 0.04), and metastases in ≥3 inguinal or pelvic lymph node regions (P = 0.02) were associated with a 15–18% risk of CI/PA recurrence. Following chemoradiotherapy, 6 patients with recurrent or primary metastatic CI/PA lymph nodes were free of recurrence at last follow-up. The overall rate of ano-inguinal lymphatic drainage (AILD) recurrence was 2 of 170 (1.2%), and among patients with inguinal metastases at initial diagnosis it was 2 of 65 (3.1%).

Conclusions

We conclude that other measures than increased margins around the primary tumor are needed to improve local control. Furthermore, metastatic CI/PA lymph nodes, either at initial diagnosis or in the recurrent setting, should be considered potentially curable. Patients with certain patterns of metastatic pelvic lymph nodes might be at an increased risk of harboring tumor cells also in the CI/PA lymph nodes.

Implantation of tissue expander prior to irradiation in the era of intensity modulated radiotherapy: impact on the management of patients with pelvic digestive cancers

PURPOSE

Before the introduction of intensity-modulated radiation therapy (IMRT), few teams used to implant a pelvic tissue expander to keep the bowel away from the radiation field, so as to reduce the risk of acute and late enteritis. However, this unexpected surgery could impact patient's overall treatment and may be no more necessary in the era of modern radiotherapy.

MATERIAL AND METHODS

This is a retrospective cross-sectional study including 13 patients who underwent tissue expander implantation before radiotherapy or chemoradiotherapy for rectal or anal carcinoma between November 2008 and March 2019. First, we aim to show that IMRT could sometimes be insufficient to respect dosimetric constraints, and then we aim to report the impact of tissue expander implantation on the global strategy of care of patients with anal and rectal cancers.

RESULTS

Seventy-seven percent of the included patients were treated for anal neoplasms, while the remaining 23% had locally advanced rectal cancer. The median follow-up since implantation of the expander was 51 months [3.7-115]. Three patients recurred. One patient developed grade III toxicity related to the implantation of a tissue expander. The delay between diagnosis and the start of irradiation was significantly prolonged (median of 3 months), requiring unusual induction chemotherapy.

CONCLUSION

Implantation of tissue expander prior to chemoradiotherapy should be considered, even in the era of IMRT, when irradiated peritoneal cavity volume (V15Gy-V45Gy) far exceeds usual dose constraints. However, it impacts the global strategy of care by delaying the start of irradiation, by introducing induction chemotherapy, and rarely by causing post-operative complications.

Pooled Analysis of external-beam RADiotherapy parameters in phase II and phase III trials in radiochemotherapy in Anal Cancer (PARADAC)

PURPOSE

Concomitant external-beam radiochemotherapy (5-fluorouracil-mitomycin C) has become the standard of care in anal cancer since the '90s. A pooled analysis of individual patient data from 7 major trials was performed quantifying the effect of radiation therapy (RT)-related parameters on the outcome of patients with anal cancer.

MATERIALS AND METHODS

Pooling databases from combined modality trials, the impact of RT parameters (total dose, gap duration, OTT: overall treatment time) on outcome including locoregional failure (LRF), 5-year progression free survival (PFS) and toxicities were investigated. Individual patient data were received for 10/13 identified published studies conducted from 1987 to 2008 (n = 3031). A Cox regression model was used (landmark = 3 months after RT for first follow-up).

RESULTS

After data inspection indicating severe heterogeneity between trials, only 1343 patients from 7/10 studies received were analysed (the most recent ones, since 1994; median follow-up = 4.1 years). A higher overall 5-year LRF rate [22.8% (95% confidence interval [CI] 22.3-27.3%)] significantly correlated with longer OTT (p = 0.03), larger tumour size (p < 0.001) and male gender (p = 0.045). Although significant differences were not observed, subset analyses for LRF (dose range: 50.4-59 Gy) seemed to favour lower doses (p = 0.412), and when comparing a 2-week gap versus 3 (dose: 59.4 Gy), results suggested 3 weeks might be detrimental (p = 0.245). For a 2-week gap versus none (dose range: 55-59.4 Gy), no difference was observed (p = 0.89). Five-year PFS was 65.7% (95% CI: 62.8-68.5%). Higher PFS rates were observed in women (p < 0.001), smaller tumour sizes (p < 0.001) and shorter OTT (p = 0.025). Five-year overall survival [76.7% (95% CI: 73.9%-79.3%)] correlated positively with female gender (p < 0.001), small tumour size (p = 0.027) and short OTT (p = 0.026). Descriptive toxicity data are presented.

CONCLUSION

For patients receiving concurrent external-beam doublet chemoradiation, a longer OTT seems detrimental to outcome. Further trials involving modern techniques may better define optimal OTT and total dose.

[Anal channel cancer: customization of dose, volume and breaching]

The conservative treatment of squamous cell carcinoma of anal canal by irradiation is recommended as first indication. Despite its rarity, significant improvements were obtained by retrospective or prospective clinical studies these 20 past years, evaluating concomitant chemotherapy and IMRT. Nevertheless, the individualisation of the treatment, over dose distribution, has poor data available. Fractionation remains classic (1.8-2.0Gy/Fr), but the optimal dose level remains under discussion. The strategy concerning the volumes and doses for the prophylactic volumes remains under discussion. This paper will describe the data published, and the recommendations of working Groups, and the main options under evaluation. To conclude, today only the absence of gap is recommended, the benefit of a one-step schedule reducing the treatment time, then increasing local control and survival, but personalised schedules remain under investigation.