Moderately Low Alpha/Beta Ratio for Rectal Cancer May Best Explain the Outcome of Three Fractionation Schedules of Preoperative Radiotherapy

Concurrent Liposomal Cisplatin (Lipoplatin), 5-Fluorouracil and Radiotherapy for the Treatment of Locally Advanced Gastric Cancer: A Phase I/II Study

“…Although the a/b value of gastric cancer is unknown, several human carcinomas, including colon adenocarcinoma, tend to have a low a/b value, so large radiotherapy fractions may be more effective. Suwinski et al recently suggested a 5-Gy value for colorectal cancer (21). The 12 and 15 fractions of 3.5 Gy used in the current study correspond to a biological dose of 52 Gy and 66 Gy, respectively, for normal tissues and cancer tissues with a/ b value as low as 4 Gy.…”

Sensitivity Analysis of Parameters in Linear-Quadratic Radiobiologic Modeling

“…This is in contrast with the effect on slopes of whole dose-response curves, where curves are unrealistically steep unless very wide distributions of a are assumed (24). For example, the first coefficient for 20 Gy  3F in Table 4 is increased from 0.68 to 0.72 when the calculations are repeated with a distribution as wide as SE = 40% for the tumor a/b of 10 Gy (25) Overall, the rate of change of head-and-neck LRC (localregional control) with total dose at constant dose per fraction, and BED or EQD2, is reported to be 1.7% absolute LRC per 1% of EQD2 or of BED. This is the average of all the 16 head-and-neck schedules listed in the comprehensive review by Okunieff et al (26), or subsequent updatings.…”

Can Radiotherapy Alone Be Effective for Treating Anastomotic Recurrence of Rectal Cancer? When the Patient Decides?

“…9,15,21 With regard to the radiotherapy treatment, several studies have reported excellent results, especially in the preoperative and also in the intraoperative treatment of a ''local recurrence.'' [23][24][25][26][27] At this point it should be stressed that the local control achieved with radiotherapy alone is due to low alpha/ beta ratio of the neoplastic cells of the rectum, 28 which allows to use single fractions of 5 Gy compared with an estimated value of 10-12 Gy used for most other cancers. According to these data and because of the absence of reports in the literature, AR could also benefit from this treatment, and in the authors' opinion, the results could be also more relevant because radiotherapy would be used to treat a smaller field.…”