Anal cancerA tumor control probability model for anal squamous cell carcinoma
Section snippets
Materials and methods
We performed a systematic review of PubMed (i.e., MEDLINE and other PubMed resources) and Embase databases in accordance to PRISMA guidelines. The searches were limited to full papers, published in the English language from January 2005 to July 2014 involving the treatment of human patients. Search terms included IMRT, intensity modulated radiotherapy, anal and anus. Four papers were excluded; two as the same series was subsequently updated in a further publication therefore the latter
Results
Thirteen publications incorporating 645 patients were identified, details of individual series are presented in Table 1 [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38].
The resulting 2-year local control predictive models for early and late stage disease are shown in Fig. 1 together with the clinical data from the individual series used for model fitting. Series with a stage mix >60% T1 and T2 are shown as points (●) and series with a stage mix >40% T3+ are shown as
Discussion
We report TCP models for early stage and late stage anal carcinoma and demonstrate a dose–response curve in both. To our knowledge a TCP model in anal cancer has not been previously published. This study highlights the role of individualised radiotherapy dose allowing dose de-escalation in early stage tumours and dose escalation in locally-advanced tumours as a platform for investigation.
Although the IMRT series are more homogeneous than previous conformal series, there remains a degree of
Conflicts of interest statement
None to declare.
Acknowledgments
M.P. is funded by CR UK grant C5255/A15935.
R.M. and M.A.H. are supported by MRC Grant MC_PC_12001/2.
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Cited by (28)
Brachytherapy boost in anal canal cancer – A GEC ESTRO PDR task force meta-analysis
2023, Clinical and Translational Radiation OncologyCompliance to chemoradiation in squamous cell carcinoma of the anus
2022, Cancer Treatment ReviewsChemoradiation for Anal Cancer: Clinical Outcomes and Strategies to Optimize the Therapeutic Ratio According to HPV Status
2021, Seminars in Radiation OncologyCitation Excerpt :As previously discussed, HPV-associated malignancies have been shown to be more radiosensitive compared to those that are HPV-negative.71 Although radiotherapy dose de-escalation has not been prospectively tested in anal cancer until recently, data from single institution series,46 large population-based cancer registries,72 and tumor control probability modeling studies73 support the notion that excellent disease control can be achieved in low-risk patients despite radiotherapy doses that are well below current standard of care recommendations. For instance, in the seminal study by Nigro et al an impressive pathologic complete response rate of 84% was achieved despite treatment with a dose of only 30 Gy, underscoring the potential to reduce radiotherapy dose without compromising disease control in patients with favorable disease characteristics.46
Anal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up<sup>☆</sup>
2021, Annals of OncologyCitation Excerpt :The total doses, including the boost doses used, vary between countries from 50.4 Gy used in the ACT II trial, 55-59 Gy for T3-4 or node-positive disease used in the RTOG 98-11 trial and up to 60 Gy used in a large series from the Nordic countries.38,39,45 Tumour control probability models suggest that lower doses may be sufficient for small tumours, while higher doses—in the range of 50-55 Gy or higher—may be required for more advanced tumours such as T3-4 or N1.46,47 It is not possible to make a definitive recommendation (based on inter-trial comparisons of differing dose fractionations with or without a treatment gap) on the type (external beam or brachytherapy) or dose for a boost after 50 Gy.