Dose-response of anal cancerClinical target volumes in anal cancer: Calculating what dose was likely to have been delivered in the UK ACT II trial protocol
Section snippets
Radiotherapy treatment planning
The ACT II protocol aimed to deliver 50.4 Gy to the primary tumour, and palpable regional lymph nodes or those nodes involved by imaging criteria or positive on biopsy, over five and a half weeks using a two-phase technique. If the regional lymph nodes were not palpably or radiologically enlarged they were intended to receive a dose of 30.6 Gy. Both phases of treatment were planned simultaneously with a CT dataset acquired prior to radiotherapy treatment.
The phase I dose was 30.6 Gy in 17
Patient and tumour characteristics
The median age was 63 years (range 38–84) with 11 males, and 22 females. Clinical staging included T1(5), T2(16), T3(7) and T4(5) and nine patients (27%) had clinically palpable or radiologically positive lymphadenopathy. The tumour site was canal in 23, anal margin in eight, and both sites in two patients. Median number of treatment days was 38 (range 38–45) with no intended treatment breaks. All 33 patients received concurrent chemotherapy. During this period, eight patients were treated
Discussion
To design a future phase III trial with appropriate doses to CTVs, we needed to calculate the doses received in the ACT II trial by both gross tumour volume and subclinical areas. However we also needed to decide a suitable prescribed planning dose to the PTV and an appropriate PTV margin expansion for 3D conformal planning. We could find no meta-analyses or systematic reviews in anal cancer to offer guidance on the optimal total dose or target definition. In addition no dose–response curves
Conclusion
The patients in our study had either been treated in the ACT II trial or planned to an identical protocol. Their stage distribution is similar. They are therefore likely to represent the population of patients with anal cancer within the whole trial, and be applicable to patients in any future trial. Our calculated doses are likely to represent doses delivered within the ACT II trial.
Dose-escalation of radiation may improve local control, particularly for cT3/T4 patients. The dose actually
Conflict of interest notification
There are no potential or actual conflicts of interest.
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Treatment of the Primary Tumor in Anal Canal Cancers
2017, Surgical Oncology Clinics of North AmericaCitation Excerpt :Inclusion of the common iliac nodes, and full coverage of the entire internal iliac nodal system, by setting the upper CTV border at or above the sacral promontory1,2 remains controversial. In ACT II the superior aspect of the initial anterior-posterior/posterior-anterior field was defined as 2 cm above the inferior aspect of the sacroiliac (SI) joints, usually at the S1/S2 interface; with beam divergence, the estimated dose to the common iliac nodes was small.45 Very few isolated recurrences are observed above this field in the ACT II dataset.4
Tumour- and treatment-related colostomy rates following mitomycin C or cisplatin chemoradiation with or without maintenance chemotherapy in squamous cell carcinoma of the anus in the ACT II trial
2014, Annals of OncologyCitation Excerpt :We attribute this to the continuous CRT schedule with no planned treatment breaks used in ACT II. In ACT I, only 40 out of 577 patients had a colostomy formed to ameliorate late effects [3], and in ACT II, this figure fell to 15 out of 940, reflecting the fact that estimated doses to the anorectal sphincter in ACT II are low [23]. The consistency of dose received in ACT II—98% of patients received 51.4 Gy to the anal sphincter with an IQR for duration of treatment 38–39 days—indicates that the data presented are robust and unique.
Intensity-modulated Radiotherapy in Anal Cancer - Where Do We Go from Here?
2013, Clinical OncologyGuidelines for delineation of pelvic lymph nodes in anal cancer treatment
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