Subcutaneous spacer injection to reduce skin toxicity in breast brachytherapy: A pilot study on mastectomy specimens

The use of hyperbaric oxygen to treat actinic rectal fistula after SpaceOAR use and radiotherapy for prostate cancer: a case report

Background

In definitive radiation therapy for prostate cancer, the SpaceOAR® System, a hydrogel spacer, is widely used to decrease the irradiated dose and toxicity of rectum. On the other hand, periprostatic abscesses formation and rectal perforation are known as rare adverse effects of SpaceOAR. Nevertheless, there is a lack of reports clarifying the association between aggravation of abscesses and radiation therapy, and hyperbaric oxygen therapy (HBOT) is effective for a peri-SpaceOAR abscess and rectal perforation.

Case presentation

We report a case of a 78-year-old high-risk prostate cancer patient. After SpaceOAR insertion into the correct space, he started to receive external beam radiation therapy (EBRT). He developed a fever, perineal pain and frequent urination after the completion of EBRT, and the magnetic resonance imaging (MRI) revealed a peri-SpaceOAR abscess. Scheduled brachytherapy was postponed, administration of antibiotics and opioid via intravenous drip was commenced, and transperineal drainage was performed. After the alleviation of the abscess, additional EBRT instead of brachytherapy was performed with MRI-guided radiation therapy (MRgRT). On the last day of the MRgRT, perineal pain reoccurred, and MRI and colonoscopy detected the rectal perforation. He received an intravenous antibiotics drip and HBOT, and fully recovered from the rectal perforation.

Conclusions

Our report indicates that EBRT can lead to a severe rectum complication by causing inflammation for patients with a peri-SpaceOAR abscess. Furthermore, HBOT was effective for the peri-SpaceOAR abscess and rectal perforation associated with EBRT.

Radiochromic film in vivo dosimetry predicts early the risk of acute skin toxicity for brachytherapy partial breast irradiation

Brachytherapy accelerated partial breast irradiation (APBI) is well tolerated, but reported acute toxicities including moist desquamation rates range from 7% to 39%. Moist desquamation is correlated to long-term skin toxicity and high skin dose is the main risk factor. This study uses radiochromic films for in vivo skin dosimetry of low dose rate (LDR) APBI brachytherapy and prediction of skin toxicity. Patients participating in a clinical trial assessing skin toxicity of LDR seed brachytherapy were included in this study. Following the seed implantation procedure, patients were asked to wear a customized oval shaped radiochromic film on the skin projection of the planned target volume (PTV) for 24 h. Exposed films were collected, and maximum point doses were measured. In addition, maximum doses to a small skin volume (D_0.2cc) were calculated on the pre- and post-implant CT-scan. Acute skin toxicities (redness, pigmentation, induration and dermatitis) were scored by the treating physician for 2 months during follow-up visits. Skin dose measurements and acute toxicity were available for 18 consecutive patients. The post-implant calculated maximum skin doses (D_0.2cc), 60.8 Gy (SD ± 41.0), were on average 30% higher than those measured in vivo (D_max-film), 46.6 Gy (SD ± 19.3), but those values were highly significantly correlated (Spearman's rho 0.827, p < 0.001). Also, dermatitis and induration were significantly correlated with higher in vivo measured and post-implant calculated skin dose. Pre-implant dosimetry was not correlated with measured or post-implant skin dose or side effects. Radiochromic films can reliably diagnose excess dose to the skin during the first 24 h and predict skin toxicity, which enables preventative measures. Trial registration: Nederlands Trial Register (www.trialregister.nl), NTR6549, the trial was registered prospectively on 27 June 2017. ABR number: NL56210.078.16.