Combined CONVentional with HYPOfractionated regimen (CONV-HYPO) alternative instead of conventionally fractionated radiotherapy to improve treatment outcomes
, 2, 2, 3
Abstract
For years, the process of accelerated repopulation recognized as a dominant factor for radiotherapy failures has been deduced rather than proved by direct clinical data. It sounds logical and that towards the end of fractionated radiotherapy residual tumor cells likely become hypoxic and resistant to conventional dose fractions. Therefore, total doses higher than 63–65 Gy are likely wasted and useless, at least for locally advanced cancers. Thus, the last few 2.0 Gy fractions should be replaced with a few large 5–10 Gy fractions. The CONV-HYPO concept is presented and discussed in detail. For years, the CONV-HYPO has mainly been explored to treat rectal cancer, and the Papillon 50 kV unit has been most often used as a HYPO contact therapy. Recently, high dose rate (HDR) brachytherapy has become a plausible alternative due to the precise equipment entering to the market. This method is presented in detail. The CONV part of 45 Gy in 25 fractions combined with Capecitabine is followed by the three-step HYPO-HDR BRT procedure consisting of 3 × 8 Gy, 3 × 10 Gy, and if it is well tolerated, then can be followed by the last step of 3 × 12 Gy. This protocol is now used in Gliwice. However, rectal cancer is not the only target for the CONV-HYPO, as it can also be effectively used to treat H&N, lung, esophageal, liver, pancreatic, prostate cancers, and soft tissue sarcomas as well.
Keywords: hypoxic tumor cellsineffective conventional irradiationCONV-HYPO conceptrectal cancerGliwice protocol
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