Re-irradiation for recurrent rectal cancer - a single-center experience

Carbon-Ion Radiation Therapy for Unresectable Locally Recurrent Colorectal Cancer: A Promising Curative Treatment for Both Radiation Therapy: Naïve Cases and Reirradiation Cases

PURPOSE

It is difficult to effectively cure patients with unresectable locally recurrent colorectal cancers (LRCRCs) using conventional chemotherapy or chemoradiation therapy. Furthermore, treatment options vary depending on the patient's history of radiation therapy. Carbon-ion radiation therapy (CIRT) is a potentially curative treatment for these patients. Here, we compare the treatment outcomes of radiation therapy-naïve cases (nRT) and re-irradiation cases (reRT).

METHODS AND MATERIALS

Patients with LRCRC treated with CIRT at QST Hospital between 2003 and 2019 were eligible. CIRT was administered daily 4 d/wk for 16 fractions. The total irradiated dose was set at 73.6 Gy (relative biologic effectiveness-weighted dose [RBE]) for nRT and 70.4 Gy (RBE) for reRT patients.

RESULTS

We included 390 nRT cases and 83 reRT cases. The median follow-up period from the initiation of CIRT was 48 (5-208) months. The 3-year overall survival (OS) rates for nRT and reRT were 73% (95% CI, 68%-77%) and 76% (65%-84%), respectively. The 5-year OS rates were 50% (45%-55%) and 50% (38%-61%), respectively. These rates did not differ significantly (P = .55). The 3-year local control (LC) rates for nRT (73.6 Gy) and reRT (70.4 Gy) cases were 80% (75%-84%) and 80% (68%-88%), respectively. The 5-year LC rates were 72% (67%-78%) and 69% (55%-81%), respectively, without a significant difference (P = .56).

CONCLUSIONS

Our results suggest that CIRT for LRCRC is a very effective and promising treatment for both nRT and reRT cases.

Particle beam therapy for pelvic recurrence of colorectal cancer: a registry data analysis in Japan and a systematic review

The aim of this study was to investigate the efficacy and safety of particle beam therapy (PBT) with proton or carbon ion beam for pelvic recurrence of colorectal cancer (PRCC) by comparing the clinical outcomes of a dataset of prospectively enrolled patients for PBT with those from the literature, which were collected by a systematic review of external X-ray radiotherapy (XRT) and PBT. Patients with PRCC treated at 14 domestic facilities between May 2016 and June 2019 and entered the database for prospective observational follow-up were analyzed. The registry data analyzed included 159 PRCC patients treated with PBT of whom 126 (79%) were treated with carbon ion radiation therapy (CIRT). The 3-year overall survival and local control rate were 81.8 and 76.4%, respectively. Among these PRCC patients, 5.7% had Grade 3 or higher toxicity. Systematic search of PubMed and Cochrane databases published from January 2000 to September 2020 resulted in 409 abstracts for the primary selection. Twelve studies fulfilled the inclusion criteria. With one additional publication, 13 studies were selected for qualitative analysis, including 9 on XRT and 4 on PBT. There were nine XRT studies, which included six on 3D conformal radiotherapy and three on stereotactic body radiation therapy, and four PBT studies included three on CIRT and one on proton therapy. A pilot meta-analysis using literatures with median survival time extractable over a 20-month observation period suggested that PBT, especially CIRT, may be a promising treatment option for PRCC not amenable to curative resection.

Development of a consensus-based delineation guideline for locally recurrent rectal cancer

BACKGROUND AND PURPOSE

Neoadjuvant chemoradiotherapy (nCRT) is used in locally recurrent rectal cancer (LRRC) to increase chances of a radical surgical resection. Delineation in LRRC is hampered by complex disease presentation and limited clinical exposure. Within the PelvEx II trial, evaluating the benefit of chemotherapy preceding nCRT for LRRC, a delineation guideline was developed by an expert LRRC team.

MATERIALS AND METHODS

Eight radiation oncologists, from Dutch and Swedish expert centres, participated in two meetings, delineating GTV and CTV in six cases. Regions at-risk for re-recurrence or irradical resection were identified by eleven expert surgeons and one expert radiologist. Target volumes were evaluated multidisciplinary. Inter-observer variation was analysed.

RESULTS

Inter-observer variation in delineation of LRRC appeared large. Multidisciplinary evaluation per case is beneficial in determining target volumes. The following consensus regarding target volumes was reached. GTV should encompass all tumour, including extension into OAR if applicable. If the tumour is in fibrosis, GTV should encompass the entire fibrotic area. Only if tumour can clearly be distinguished from fibrosis, GTV may be reduced, as long as the entire fibrotic area is covered by the CTV. CTV is GTV with a 1 cm margin and should encompass all at-risk regions for irradical resection or re-recurrence. CTV should not be adjusted towards other organs. Multifocal recurrences should be encompassed in one CTV. Elective nodal delineation is only advised in radiotherapy-naïve patients.

CONCLUSION

This study provides a first consensus-based delineation guideline for LRRC. Analyses of re-recurrences is needed to understand disease behaviour and to optimize delineation guidelines accordingly.