Background
Advanced pelvic radiotherapy techniques aim to reduce late bowel toxicity which can severely impact the lives of pelvic cancer survivors. Although advanced techniques have been largely adopted worldwide, to achieve their aim, knowledge of which dose-volume parameters of which components of bowel predict late bowel toxicity is crucial to make best use of these techniques.
The rectum is an extensively studied organ at risk (OAR), and dose-volume predictors of late toxicity for the rectum are established. However, for other components of bowel, there is a significant paucity of knowledge. The Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) reviews recommend dose-volume constraints for acute bowel toxicity for peritoneal cavity and bowel loops, although no constraints are recommended for late toxicity, despite its relevance to our increasing number of survivors. This systematic review aims to examine the published literature to seek dose-volume predictors and constraints of late bowel toxicity for OARs (apart from the rectum) for use in clinical practice.
Methods
A systematic literature search was performed using Medline, Embase, Cochrane Library, Web of Science, Cinahl and Pubmed. Studies were screened and included according to specific pre-defined criteria. Included studies were assessed for quality against QUANTEC-defined assessment criteria.
Results
101 studies were screened to find 30 relevant studies. Eight studies related to whole bowel, 11 to small bowel, and 21 to large bowel (including 16 of the anal canal). The anal canal is an important OAR for the development of late toxicity, and we recommend an anal canal Dmean <40Gy as a constraint to reduce late incontinence. For other components of bowel (sigmoid, large bowel, intestinal cavity, bowel loops), although individual studies found statistically significant parameters and constraints these findings were not corroborated in other studies.
Conclusions
The anal canal is an important OAR for the development of late bowel toxicity symptoms. Further validation of the constraints found for other components of bowel is needed. Studies that were more conclusive included those with patient-reported data, where individual symptom scores were assessed rather than an overall score, and those that followed statistical and endpoint criteria as defined by QUANTEC.
Background: Optimal therapy for radically treated SCLC is concurrent hyperfractionated chemoradiotherapy (CCRT-45 Gy/30fractions/3 weeks, 3-D conformal) and prophylactic cranial irradiation (after complete or a good partial response). CCRT is not always feasible; patients may then have sequential chemoradiotherapy (SCRT)-45 Gy/15 fractions/3 weeks, 2D or 3D planned. Methods: CCRT and 3D planning were introduced locally in 2010. We reviewed all SCLC cases treated with both chemotherapy (CT) and radiotherapy (RT) with potentially curative intent between 2010 and 2014 at Velindre Cancer Centre. Results: 87 patients were treated. 86 received both CT and RT (73 sequential and 13 concurrent). One deteriorated after cycle 1 chemotherapy (further CT/RT cancelled). The median age was 66 (range 36-85). 51 were female, 36 were male. WHO PS at presentation: 0-36%, 1-43%, 2-18%, 3-2%. 70% had stage III disease. 44 patients had 2D RT planning; 42 patients had 3D; 3D planning increased over time. Only 15% received CCRT.
The therapeutic value of sequential hemi-body irradiation (HBI) as a primary treatment for small-cell lung cancer (SCLC) was compared to 3-drug cyclic chemotherapy (CC) in a group of 64 patients with early and advanced disease. Thirty patients were randomized to receive sequential HBI and 34 to receive CC. All patients received a local radiation boost to the primary lesion. An overall response rate of 87% was obtained in patients treated with sequential HBI and 88% in patients treated with CC. In patients with early disease, the estimated median survival was 43 weeks when treated with HBI and 42 weeks when treated with CC, but in advanced disease the estimated median survival was 15 weeks and 44 weeks respectively. Of the patients with an initial complete response, the estimated median survival was 51 weeks for HBI and 62 weeks for CC. From these observations we suggest that sequential HBI treatment technique with local radiation boost is an efficient method of tumour control in patients with early small-cell lung cancer.
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