Epinal #2: 409 Patients Overexposed during Radiotherapy for Prostate Cancer after Daily Use of Portal Imaging Controls

Between 1987 and 2006, the Radiotherapy department of the Jean Monnet Hospital in Épinal (France) had a series of mistakes leading to overexposure of many patients. We report the second accident identified in March 2007, and describe its consequences, on the 409 affected patients. In 2000, the radiation therapy team implemented three dimensional conformal radiotherapy (3D-CRT) to treat patients with prostate cancer. The quality control of patient repositioning was assessed with daily portal imaging (PI). The “Institut de Radioprotection et de Sûreté Nucléaire” (IRSN) reconstructed doses delivered by those PI after the discovery of the accident and found that each week, 4 sessions were conducted after 2 PI delivering 0.17 Gy, and one session was conducted after 6 IP delivering 0.36 Gy. These additional doses were not subtracted from the prescribed fraction dose (2 Gy). Between October 2000 and October 2006, 433 patients were treated with 3D-CRT for prostate cancer. Twenty-four of these patients were victims of the first accident, not described here, due to incorrect use of a treatment planning system, and are reported in another report. For prescribed doses of 70 Gy to 78 Gy, total doses received by 409 patients ranged from 77 Gy to 81 Gy in 35 to 39 fractions, corresponding to 8% to 10% overexposure. All these patients were evaluated starting March 2007, and were informed of their irradiation conditions. Of 409 patients, 405 were evaluable for toxicity. One hundred fifty-five patients (38%) developed Grade ≥ late gastrointestinal toxicities with rectal bleeding, and 66 patients (16%) developed Grade 3 proctitis that was treated with argon plasma coagulation, or required blood transfusions for hematologic support. Two patients developed Grade 4 rectal fistula and died. Of the 409 patients, 72 were irradiated for rising PSA after prostatectomy, 69 of them were evaluable for urinary toxicity. Thirty-six patients (54%) had Grade ≥ 2 permanent urinary incontinence requiring protective padding, and 9 patients (13%) developed Grade ≥ 2 hematuria. Of 330 evaluable patients treated with definitive radiotherapy, 56 (17%) experienced Grade ≥ 2 chronic frequency and urgency, and 35 (11%) had Grade ≥ 2 permanent urinary incontinence. This accident highlights the importance of the dose delivered with the PI controls during 3D-CRT. Doses given by PI should be integrated in the dose calculation of each session. The complications observed in this cohort emphasize the importance of the dose per fraction (here 2.17 to 2.36 Gy) in the genesis of late complications after radiotherapy.