Advanced radiation therapy technologies in the treatment of rectal and anal cancer: intensity-modulated photon therapy and proton therapy

Comparison of the TNM9th and 8th editions for localized and locally advanced anal squamous cell carcinoma treated nonsurgically and proposal of a new stage grouping system

OBJECTIVE

To compare the survival discrimination of the TNM9th and 8th editions for localized and locally advanced anal squamous cell carcinoma (ASCC) treated nonsurgically and suggest a simple revised staging system with data from the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

Overall survival (OS) was the primary endpoint. Survival comparisons between the T and N stages and the different staging systems were performed using the Kaplan-Meier method and log-rank test, followed by correlation analysis and variable importance analysis (VIA). Additionally, multivariate analysis was employed to identify significant predictors, which were further visualized using a nomogram. Finally, calibration curve, C-index, and decision curve analysis (DCA) were applied to assess the performance of the different staging systems.

RESULTS

A total of 5384 patients with ASCC were analyzed, revealing superior discrimination OS by the TNM9th edition compared to that by the TNM8th edition. Multivariate analysis identified the T and N stages as significant OS predictors (all p < 0.001). However, ambiguity persisted in stage III subgroups within the TNM9th edition, showing OS times of 102 months for stage IIIA disease, 88 months for stage IIIB disease, and 128 months for stage IIIC disease (all p > 0.05). Correlation analysis demonstrated an increased correlation for the T stage between the TNM8th and 9th editions (ρ value from 0.7 to 0.89), while the N stage correlation decreased (ρ value from 0.84 to 0.56). VIA and the prognostic nomogram highlighted the greater importance of the T stage over the N stage. Based on these findings, a new staging system was developed, and its clinical utility was confirmed through calibration curves, C-index values (from 0.598 to 0.604), and DCAs.

CONCLUSIONS

Our new staging system exhibited slightly better prognostic value compared to the TNM9th staging systems for nonmetastatic ASCC and warrants further validation.

Multi-institutional Comparison of Intensity Modulated Photon Versus Proton Radiation Therapy in the Management of Squamous Cell Carcinoma of the Anus

Purpose

Concurrent chemoradiation therapy is a curative treatment for squamous cell carcinoma of the anus, but patients can suffer from significant treatment-related toxicities. This study was undertaken to determine whether intensity modulated proton therapy (IMPT) is associated with less acute toxicity than intensity modulated radiation therapy (IMRT) using photons.

Materials and Methods

We performed a multi-institutional retrospective study comparing toxicity and oncologic outcomes of IMRT versus IMPT. Patients with stage I-IV (for positive infrarenal para-aortic or common iliac nodes only) squamous cell carcinoma of the anus, as defined by the American Joint Committee on Cancer's AJCC Staging Manual, eighth edition, were included. Patients with nonsquamous histology or mixed IMPT and IMRT treatment courses were excluded. Acute nonhematologic toxicities, per the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE), version 4, were recorded prospectively at all sites. Acute and late toxicities, dose metrics, and oncologic outcomes were compared between IMRT and IMPT using univariable and multivariable statistical methods. To improve the robustness of our analysis, we also analyzed the data using propensity score weighting methods.

Results

A total of 208 patients were treated with either IMPT (58 patients) or IMRT (150 patients). Of the 208 total patients, 13% had stage I disease, 36% stage II, 50% stage III, and 1% stage IV. IMPT reduced the volume of normal tissue receiving low-dose radiation but not high-dose radiation to bladder and bowel. There was no significant difference between treatment groups in overall grade 3 or greater acute toxicity (IMRT, 68%; IMPT, 67%; P = .96) or 2-year overall grade 3 or greater late toxicity (IMRT, 3.5%; IMPT, 1.8%; P = .88). There was no significant difference in 2-year progression-free survival (hazard ratio, 0.8; 95% CI, 0.3-2.0).

Conclusions

Despite reducing the volume of normal tissue receiving low-dose radiation, IMPT was not associated with decreased grade 3 or greater acute toxicity as measured by CTCAE. Additional follow-up is needed to assess whether important differences arise in late toxicities and if further prospective evaluation is warranted.

Evolution of the Role of Radiotherapy for Anal Cancer

Prior to the 1980s, the primary management of localized anal cancer was surgical resection. Dr. Norman Nigro and colleagues introduced neoadjuvant chemoradiotherapy prior to abdominoperineal resection. Chemoradiotherapy 5-fluorouracil and mitomycin C afforded patients complete pathologic response and obviated the need for upfront surgery. More recent studies have attempted to alter or exclude chemotherapy used in the Nigro regimen to mitigate toxicity, often with worse outcomes. Reductions in acute adverse effects have been associated with marked advancements in radiotherapy delivery using intensity-modulated radiation therapy (IMRT) and image-guidance radiation delivery, resulting in increased tolerance to greater radiation doses. Ongoing trials are attempting to improve IMRT-based treatment of locally advanced disease with efforts to increase personalized treatment. Studies are also examining the role of newer treatment modalities such as proton therapy in treating anal cancer. Here we review the evolution of radiotherapy for anal cancer and describe recent advances. We also elaborate on radiotherapy's role in locally persistent or recurrent anal cancer.

Proton beam radiotherapy for anal and rectal cancers

Gastrointestinal cancers are bordered by radiosensitive visceral organs, resulting in a narrow therapeutic window. The search for more efficacious and tolerable therapies raises the possibility that proton beam therapy's (PBT) physical and dosimetric differences from conventional therapy may be better suited to treat both primary and recurrent disease, which carries its own unique challenges. Currently, the maximal efficacy of radiation plans for primary and recurrent anorectal cancer is constrained by delivery techniques and modalities which must consider feasibility challenges and toxicity secondary to exposure of organs at risk (OARs). Studies using volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) demonstrate that more precise dose delivery to target volumes improves local control rates and reduces complications. By reducing the low-to-moderate radiation dose-bath to bone marrow, small and large bowel, and skin, PBT may offer an improved side-effect profile. The potential to reduce toxicity, increase patient compliance, minimize treatment breaks, and enable dose escalation or hypofractionation is appealing. In cases where prognosis is favorable, PBT may mitigate long-term morbidity such as secondary malignancies, femoral fractures, and small bowel obstruction.

The efficacy of human placenta-derived mesenchymal stem cells on radiation enteropathy along with proteomic biomarkers predicting a favorable response

BACKGROUND

Radiation enteropathy is a common complication in patients with abdominopelvic cancer, but no treatment has yet been established. Stem cell therapy may be a viable therapeutic option because intestinal stem cells are highly vulnerable to ionizing radiation (IR) and stem cell loss explains its intractability to general treatment. Here, we investigated either prophylactic or therapeutic efficacy of human placenta-derived mesenchymal stem cells (hPDSCs) against radiation enteropathy and could identify biomarkers predicting a favorable response to stem cell therapy.

METHODS

We challenged a radiation-induced enteropathy model with hPDSCs. After sacrifice, we checked the gross anatomy of small intestine, histology gross, and analyzed that, accompanied with molecular changes implicated in this model.

RESULTS

hPDSCs significantly improved the outcome of mice induced with either radiation enteropathy or lethal radiation syndrome (P < 0.01). hPDSCs exerted inhibitory actions on inflammatory cytokines, the re-establishment of epithelium homeostasis was completed with increasing endogenous restorative processes as assessed with increased levels of proliferative markers in the hPDSCs group, and a significant inhibition of IR-induced apoptosis. The preservation of cells expressing lysozyme, and Musashi-1 were significantly increased in the hPDSC treatment group. Both preventive and therapeutic efficacies of hPDSCs were noted against IR-induced enteropathy. Label-free quantification was used to identify biomarkers which predict favorable responses after hPDSC treatment, and finally glutathione S-transferase-mu type, interleukin-10, and peroxiredoxin-2 were validated as proteomic biomarkers predicting a favorable response to hPDSCs in radiation enteropathy.

CONCLUSIONS

hPDSCs may be a useful prophylactic and therapeutic cell therapy for radiation enteropathy.

Definitive high-dose radiotherapy with concurrent chemotherapy for locally advanced rectal cancer: A case report and literature review

BACKGROUND

Standard management for locally advanced rectal cancer (LARC) involves preoperative chemoradiotherapy (CRT) and radical surgery. However, this level of treatment may be unnecessary for a subgroup of LARC patients. Previous reports have shown that approximately 20% of LARC patients experience a complete tumor response to preoperative CRT. Post-CRT nonoperative management of these patients may prevent morbidities associated with radical surgery. To our knowledge, this case report firstly presents the favorable long-term outcomes of a LARC patient who underwent definitive aim CRT.

METHODS

The patient was 73 years' old, and staging workups revealed T3N2bM0 rectal adenocarcinoma. He agreed to receive CRT, but refused surgery. A radiotherapy (RT) dose of 64.8 Gy was prescribed, which was higher than conventional (50.4 Gy) preoperative aim RT. The regimen of concurrent chemotherapy was the same as that used in preoperative aim CRT: 2 cycles of 5-fluorouracil and leucovorin.

RESULTS

Three months after CRT completion, a complete tumor response was identified clinically. Colonoscopic biopsy after 1 year showed no tumor cells. This patient is alive after 4 years with no evidence of recurrence or severe toxicity.

CONCLUSION

The long-term outcomes of this case indicate the feasibility of definitive high-dose RT with concurrent chemotherapy for LARC.

Squamous-cell carcinoma of the anus: progress in radiotherapy treatment

Chemoradiotherapy is the standard-of-care treatment of squamous-cell carcinoma of the anus (SCCA), and this has not changed in decades. Radiation doses of 50-60 Gy, as used in many phase III trials, result in substantial late morbidities and fail to control larger and node-positive tumours. Technological advances in radiation therapy are improving patient outcomes and quality of life, and should be applied to patients with SCCA. Modern techniques such as intensity-modulated radiotherapy (IMRT), rotational IMRT, image-guided radiotherapy using cone-beam CT, and stereotactic techniques have enabled smaller margins and highly conformal plans, resulting in decreased radiation doses to the organs at risk and ensuring a shorter overall treatment time. In this Perspectives article, the use of novel approaches to target delineation, optimized radiotherapy techniques, adaptive radiotherapy, dose-escalation with external-beam radiotherapy (EBRT) or brachytherapy, and the potential for modified fractionation are discussed in the context of SCCA.

Radiation proctopathy

Radiation therapy is a widely utilized treatment modality for pelvic malignancies, including prostate cancer, rectal cancer, and cervical cancer. Given its fixed position in the pelvis, the rectum is at a high risk for injury secondary to ionizing radiation. Despite advances made in radiation science, up to 75% of the patients will suffer from acute radiation proctitis and up to 20% may experience chronic symptoms. Symptoms can be variable and include diarrhea, bleeding, incontinence, and fistulization. A multitude of treatment options exist. This article summarizes the latest knowledge relating to radiation proctopathy focusing on the vast array of treatment options.

Dosimetric comparative study of 3 different postoperative radiotherapy techniques (3D-CRT, IMRT, and RapidArc) for II-III stage rectal cancer

Postoperative radiotherapy is critical for reducing local relapse for advanced rectal carcinoma but has many side effects. Our study compared the dose distribution of target volumes, protection of normal organs at risk (OAR), and monitor unit (MU) for 3 radiotherapy techniques (3-dimensional conformal radiation therapy [3D-CRT], intensity-modulated radiation therapy [IMRT], and RapidArc (Varian Medical Systems, Inc., Palo Alto, CA, USA)). The results advocate for the clinical application of RapidArc technique in the future.Thirty postoperative patients with rectal cancer were enrolled. The 3 radiotherapy plans mentioned above were designed for each patient. The target volume coverage indicators included average dose, conformity index (CI), and homogeneity index (HI) of planning tumor volume (PTV). OAR included the bladder, small intestine, colon, and bilateral proximal femurs. The 30 patients were divided into 3 groups (10 cases in each group) for postoperative radiotherapy with the 3D-CRT, IMRT, or RapidArc technique, respectively.Both the IMRT and RapidArc plans have a significantly higher average PTV dose and better CI and HI (P < 0.01) than 3D-CRT. IMRT and RapidArc result in significantly lower doses of irradiation for all the OAR examined. Both the IMRT and RapidArc plans have a significantly lower V40 of the bladder, small intestine, and colon than 3D-CRT (P < 0.01). The IMRT and RapidArc plans can also reduce the maximum dose (Dmax) for the left proximal femur, V30, and V40 of bilateral proximal femurs compared with 3D-CRT (P < 0.01). Compared with IMRT, RapidArc can further reduce the Dmax of the small intestine, the Dmax and V30 of the bilateral proximal femurs, and the V40 of the right proximal femur (P < 0.01). RapidArc reduces MU remarkably compared with IMRT (P < 0.01). Regarding acute side effects, IMRT and RapidArc can greatly reduce the incidence of grade 3 radiation-induced cystitis and grade 2 enteritis.Both IMRT and RapidArc are better than 3D-CRT regarding PTV coverage and OAR protection. Furthermore, RapidArc is superior to IMRT regarding protection of the small intestine and bilateral proximal femurs and requires a reduced treatment time. RapidArc could be widely applied for postoperative radiotherapy for patients with ΙΙ-ΙΙΙ stage rectal cancer.

Is elective inguinal radiotherapy necessary for locally advanced rectal adenocarcinoma invading anal canal?

BACKGROUND

We investigated whether routine elective irradiation of a clinically negative inguinal node (IGN) is necessary for patients with locally advanced distal rectal cancer and anal canal invasion (ACI).

METHODS

We reviewed retrospectively 1,246 patients with locally advanced rectal adenocarcinoma managed using preoperative or postoperative chemoradiotherapy and radical surgery between 2001 and 2011. The patients' IGN was clinically negative at presentation and IGN irradiation was not performed. ACI was defined as the lower edge of the tumor being within 3 cm of the anal verge. Patients were divided into two groups, those with ACI (n = 189, 15.2%) and without ACI (n = 1,057, 84.8%).

RESULTS

The follow-up period was a median of 66 months (range, 3-142 months). Among the 1,246 patients, 10 developed IGN recurrence; 7 with ACI and 3 without ACI. The actuarial IGN recurrence rate at 5 years was 0.7%; 3.5% and 0.2% in patients with and without ACI, respectively (p < 0.001). Isolated IGN recurrence occurred in three patients, all of whom had ACI tumors. These three patients received curative intent local treatments, and one was alive with no evidence of disease 10 years after IGN recurrence. Salvage treatments in the other two patients controlled successfully the IGN recurrence for >5 years, but they developed second malignancy or pelvic and distant recurrences. Seven patients with non-isolated IGN recurrence died of disease at 5-22 months after IGN recurrence.

CONCLUSION

The low IGN recurrence rate even with ACI and the feasibility of salvage of isolated IGN recurrence indicated that routine elective IGN irradiation is not necessary for rectal cancer with ACI.

Autophagy prevents irradiation injury and maintains stemness through decreasing ROS generation in mesenchymal stem cells

Stem cells were characterized by their stemness: self-renewal and pluripotency. Mesenchymal stem cells (MSCs) are a unique type of adult stem cells that have been proven to be involved in tissue repair, immunoloregulation and tumorigenesis. Irradiation is a well-known factor that leads to functional obstacle in stem cells. However, the mechanism of stemness maintenance in human MSCs exposed to irradiation remains unknown. We demonstrated that irradiation could induce reactive oxygen species (ROS) accumulation that resulted in DNA damage and stemness injury in MSCs. Autophagy induced by starvation or rapamycin can reduce ROS accumulation-associated DNA damage and maintain stemness in MSCs. Further, inhibition of autophagy leads to augment of ROS accumulation and DNA damage, which results in the loss of stemness in MSCs. Our results indicate that autophagy may have an important role in protecting stemness of MSCs from irradiation injury.

Gastrointestinal radiation injury: Symptoms, risk factors and mechanisms

Ionising radiation therapy is a common treatment modality for different types of cancer and its use is expected to increase with advances in screening and early detection of cancer. Radiation injury to the gastrointestinal tract is important factor working against better utility of this important therapeutic modality. Cancer survivors can suffer a wide variety of acute and chronic symptoms following radiotherapy, which significantly reduces their quality of life as well as adding an extra burden to the cost of health care. The accurate diagnosis and treatment of intestinal radiation injury often represents a clinical challenge to practicing physicians in both gastroenterology and oncology. Despite the growing recognition of the problem and some advances in understanding the cellular and molecular mechanisms of radiation injury, relatively little is known about the pathophysiology of gastrointestinal radiation injury or any possible susceptibility factors that could aggravate its severity. The aims of this review are to examine the various clinical manifestations of post-radiation gastrointestinal symptoms, to discuss possible patient and treatment factors implicated in normal gastrointestinal tissue radiosensitivity and to outline different mechanisms of intestinal tissue injury.

Gastrointestinal radiation injury: Prevention and treatment

With the recent advances in detection and treatment of cancer, there is an increasing emphasis on the efficacy and safety aspects of cancer therapy. Radiation therapy is a common treatment for a wide variety of cancers, either alone or in combination with other treatments. Ionising radiation injury to the gastrointestinal tract is a frequent side effect of radiation therapy and a considerable proportion of patients suffer acute or chronic gastrointestinal symptoms as a result. These side effects often cause morbidity and may in some cases lower the efficacy of radiotherapy treatment. Radiation injury to the gastrointestinal tract can be minimised by either of two strategies: technical strategies which aim to physically shift radiation dose away from the normal intestinal tissues, and biological strategies which aim to modulate the normal tissue response to ionising radiation or to increase its resistance to it. Although considerable improvement in the safety of radiotherapy treatment has been achieved through the use of modern optimised planning and delivery techniques, biological techniques may offer additional further promise. Different agents have been used to prevent or minimize the severity of gastrointestinal injury induced by ionising radiation exposure, including biological, chemical and pharmacological agents. In this review we aim to discuss various technical strategies to prevent gastrointestinal injury during cancer radiotherapy, examine the different therapeutic options for acute and chronic gastrointestinal radiation injury and outline some examples of research directions and considerations for prevention at a pre-clinical level.

Concurrent chemoradiotherapy followed by metastasectomy converts to survival benefit in stage IV rectum cancer

BACKGROUND

To investigate the impact of concurrent chemoradiotherapy (CCRT) on stage IV rectum cancer.

METHODS

Between 2000 and 2011, 297 consecutive patients diagnosed with stage IV rectum cancer (synchronous metastasis) were enrolled. Cox proportional hazard analyses were used for prognostic factors determination, and the Kaplan-Meier method was used for survival analyses. Propensity scores with the one-to-one nearest-neighbor matching model were used to select matched patients for validation studies.

RESULTS

In total, 63 patients received CCRT and 234 did not. The patients in the CCRT group were younger, had more low-lying lesions, and had more T4 lesions, lung metastases, metastasectomies, and oxaliplatin-based upfront chemotherapy. Before propensity-score matching, a younger age (HR = 0.662, P = 0.016), lower carcinoembryonic antigen (CEA) level (≤20 ng/ml) (HR = 0.531, P = 0.001), no metastasectomy (HR = 3.214, P < 0.001), and no CCRT (HR = 1.844, P = 0.019) were independent prognostic factors after controlling for other confounding factors. After matching, only CEA and metastasectomy, but not CCRT, were independent prognostic factors. The survival benefit of CCRT was restricted to patients who undergo subsequent metastasectomy.

CONCLUSIONS

Upfront CCRT only provided a survival benefit in patients with stage IV rectum cancer who undergo subsequent metastasectomy.

Shifting concepts in rectal cancer management: a review of contemporary primary rectal cancer treatment strategies

The management of rectal cancer has transformed over the last 3 decades and continues to evolve. Some of these changes parallel progress made with other cancers: refinement of surgical technique to improve organ preservation, selective use of neoadjuvant (and adjuvant) therapy, and emergence of criteria suggesting a role for individually tailored therapy. Other changes are driven by fairly unique issues including functional considerations, rectal anatomic features, and surgical technical issues. Further complexity is due to the variety of staging modalities (each with its own limitations), neoadjuvant treatment alternatives, and competing strategies for sequencing multimodal treatment even for nonmetastatic disease. Importantly, observations of tumor response made in the era of neoadjuvant therapy are reshaping some traditionally held concepts about tumor behavior. Frameworks for prioritizing and integrating complex data can help to formulate treatment plans for patients.

Unique considerations in the patient with rectal cancer

In the past two decades, substantial progress has been made in the adjuvant management of colorectal cancer. Chemotherapy has improved overall survival in patients with node-positive (N+) disease. In contrast with colon cancer, which has a low incidence of local recurrence, patients with rectal cancer have a higher incidence requiring the addition of pelvic radiation therapy (chemoradiation). Patients with rectal cancer have a number of unique management considerations: for example, the role of short-course radiation, whether postoperative adjuvant chemotherapy is necessary for all patients, and if the type of surgery following chemoradiation should be based on the response rate. More accurate imaging techniques and/or molecular markers may help identify patients with positive pelvic nodes to reduce the chance of overtreatment with preoperative therapy. Will more effective systemic agents both improve the results of radiation as well as modify the need for pelvic radiation? This review will address these and other controversies specific to patients with rectal cancer.

Chemoradiation for rectal cancer: rationale, approaches, and controversies

The standard adjuvant treatment of cT3 and/or N+ rectal cancer is preoperative chemoradiation. However, there are many controversies regarding this approach. These controversies include the role of short course radiation, whether postoperative adjuvant chemotherapy is necessary for all patients, and if the type of surgery following chemoradiation should be based on the response rate. More accurate imaging techniques and/or molecular markers may help identify patients with positive pelvic nodes to reduce the chance of overtreatment with preoperative therapy. Will more effective systemic agents both improve the results of radiation, as well as modify the need for pelvic radiation? These questions and others remain active areas of clinical investigation.

Combined modality therapy for rectal cancer

The standard adjuvant treatment for cT3 and/or N+ rectal cancer is preoperative chemoradiation. However, there are many controversies regarding this approach. These include the role of short course radiation, whether postoperative adjuvant chemotherapy necessary for all patients and whether the type of surgery after chemoradiation should be based on the response rate. More accurate imaging techniques and/or molecular markers may help identify patients with positive pelvic nodes to reduce the chance of overtreatment with preoperative therapy. Will more effective systemic agents both improve the results of radiation as well as modify the need for pelvic radiation? These questions and others remain active areas of clinical investigation.

Colorectal cancer

Substantial progress has been made in colorectal cancer in the past decade. Screening, used to identify individuals at an early stage, has improved outcome. There is greater understanding of the genetic basis of inherited colorectal cancer and identification of patients at risk. Optimisation of surgery for patients with localised disease has had a major effect on survival at 5 years and 10 years. For rectal cancer, identification of patients at greatest risk of local failure is important in the selection of patients for preoperative chemoradiation, a strategy proven to improve outcomes in these patients. Stringent postoperative follow-up helps the early identification of potentially radically treatable oligometastatic disease and improves long-term survival. Treatment with adjuvant fluoropyrimidine for colon and rectal cancers further improves survival, more so in stage III than in stage II disease, and oxaliplatin-based combination chemotherapy is now routinely used for stage III disease, although efficacy must be carefully balanced against toxicity. In stage II disease, molecular markers such as microsatellite instability might help select patients for treatment. The integration of targeted treatments with conventional cytotoxic drugs has expanded the treatment of metastatic disease resulting in incremental survival gains. However, biomarker development is essential to aid selection of patients likely to respond to therapy, thereby rationalising treatments and improving outcomes.

Helical Tomotherapy Significantly Reduces Dose to Normal Tissues When Compared to 3D-CRT for Locally Advanced Rectal Cancer

Combined modality treatment (neoadjuvant chemoradiotherapy followed by surgery) for locally advanced rectal cancer requires special attention to various organs at risk (OAR). As a result, the use of conformal dose delivery methods has become more common in this disease setting. Helical tomotherapy is an image-guided intensity modulated delivery system that delivers dose in a fan-beam manner at 7 degree intervals around the patient and can potentially limit normal tissue from high dose radiation while adequately treating targets. In this study we dosimetrically compare helical tomotherapy to 3D-CRT for stage T3 rectal cancer. The helical tomotherapy plans were optimized in the TomoPlan system to achieve an equivalent uniform dose of 45 Gy for 10 patients with T3N0M0 disease that was at least 5cm from the anal verge. The GTV included the rectal thickening and mass evident on colonoscopy and CT scan as well as with the help of a colorectal surgeon. The CTV included the internal iliac, obturator, and pre-sacral lymphatic chains. The OAR that were outlined included the small bowel, pelvic bone marrow, femoral heads, and bladder. Anatom-e system was used to assist in delineating GTV, CTV and OAR. These 10 plans were then duplicated and optimized into 3-field 3D-CRT plans within the Pinnacle planning system. The V[45], V[40], V[30], V[20], V[10], and mean dose to the OAR were compared between the helical tomotherapy and 3D-CRT plans. Statistically significant differences were achieved in the doses to all OAR, including all volumes and means except for V[10] for the small bowel and the femoral heads. Adequate dosimetric coverage of targets were achieved with both helical tomotherapy and 3D-CRT. Helical tomotherapy reduces the volume of normal tissue receiving high-dose RT when compared to 3D-CRT treatment. Both modalities adequately dose the tumor. Clinical studies addressing the dosimetric benefits are on-going.

Radiation dose associated with local control in advanced anal cancer: retrospective analysis of 129 patients

BACKGROUND AND PURPOSE

To retrospectively analyse a large consecutive cohort of patients with anal cancer for treatment-related factors influencing local control and survival.

MATERIALS AND METHODS

All patients referred for primary radiotherapy at Medical University of Vienna in 1990-2002 with anal canal carcinoma without distant metastases were analysed. Treatment consisted of external radiotherapy with or without brachytherapy and with or without chemotherapy. Patient-, tumour-, and treatment-factors were tested for influence on survival and local control using Cox multivariate analysis.

RESULTS

Median age was 67 years (n=129), the UICC stage distribution was 15%, 58%, and 27% for stages I, II, and III, respectively. With median follow-up of 8.0 years for surviving patients (3.9 years including deceased patients), five-year overall survival and disease-free-survival were 57% and 51%, respectively. Local control at 5 years was 87%. Stage and age were significant factors for overall and colostomy-free-survival, N-stage for disease-free-survival. Shorter overall treatment time favoured local control in stage T1-2 (p=.015), higher total radiation dose and female gender were associated with improved local control in T3-4 tumours (p=.021).

CONCLUSIONS

These results support potential improvement of anal cancer treatment by studying advanced technology such as IMRT, making it possible to tailor high-dose regions.

Patterns of locoregional recurrence after surgery and radiotherapy or chemoradiation for rectal cancer

PURPOSE

To identify patterns of locoregional recurrence in patients treated with surgery and preoperative or postoperative radiotherapy or chemoradiation for rectal cancer.

METHODS AND MATERIALS

Between November 1989 and October 2001, 554 patients with rectal cancer were treated with surgery and preoperative (85%) or postoperative (15%) radiotherapy, with 95% receiving concurrent chemotherapy. Among these patients, 46 had locoregional recurrence as the first site of failure. Computed tomography images showing the site of recurrence and radiotherapy simulation films were available for 36 of the 46 patients. Computed tomography images were used to identify the sites of recurrence and correlate the sites to radiotherapy fields in these 36 patients.

RESULTS

The estimated 5-year locoregional control rate was 91%. The 36 patients in the study had locoregional recurrences at 43 sites. There were 28 (65%) in-field, 7 (16%) marginal, and 8 (19%) out-of-field recurrences. Among the in-field recurrences, 15 (56%) occurred in the low pelvis, 6 (22%) in the presacral region, 4 (15%) in the mid-pelvis, and 2 (7%) in the high pelvis. Clinical T stage, pathologic T stage, and pathologic N stage were significantly associated with the risk of in-field locoregional recurrence. The median survival after locoregional recurrence was 24.6 months.

CONCLUSIONS

Patients treated with surgery and radiotherapy or chemoradiation for rectal cancer had a low risk of locoregional recurrence, with the majority of recurrences occurring within the radiation field. Because 78% of in-field recurrences occur in the low pelvic and presacral regions, consideration should be given to including the low pelvic and presacral regions in the radiotherapy boost field, especially in patients at high risk of recurrence.

Phase I-II trial of concurrent capecitabine and oxaliplatin with preoperative intensity-modulated radiotherapy in patients with locally advanced rectal cancer

PURPOSE

To identify the maximal tolerated dose level of preoperative intensity-modulated radiotherapy combined with capecitabine and oxaliplatin and to evaluate the efficacy.

PATIENTS AND METHODS

Patients with rectal T3-T4 and/or N0-N+ rectal cancer received capecitabine 825 mg/m(2) twice daily Monday through Friday and oxaliplatin 60 mg/m(2) intravenously on Days 1, 8, and 15, concurrently with intensity-modulated radiotherapy. The radiation dose was increased in 5.0-Gy steps in cohorts of 3 patients starting from 37.5 Gy in 15 fractions (dose level [DL] 1). DL2 and DL3 were designed to reach 42.5 Gy in 17 fractions and 47.5 Gy in 19 fractions, respectively.

RESULTS

No dose-limiting toxicity was observed at DL1 or DL2. Of the 3 patients treated at DL3, 1 presented with Grade 3 diarrhea, which was considered a dose-limiting toxicity, and 3 additional patients were added. Of the 6 patients treated at DL3, no new dose-limiting toxicities were observed, and DL3 was identified as the recommended dose in this study. Eight additional patients were treated at 47.5 Gy. Grade 2 proctitis was the most frequent adverse event (40%); Grade 3 diarrhea occurred in 2 patients (10%). All patients underwent surgery, and 17 patients (85%) underwent R0 resection. Four patients (20%) presented with a histologic response of Grade 4, 11 (55%) with Grade 3+, 2 (15%) with Grade 3, and 2 patients (10%) with Grade 2.

CONCLUSION

The maximal tolerated dose in this study was 47.5 Gy. The high rates of pathologic response of Grade 3+ and 4 must be confirmed through the accrual of new patients in the Phase II study.