Role of high-dose salvage radiotherapy for oligometastases of the localised abdominal/pelvic lymph nodes: A retrospective study

Abstract

Background: Abdominal/pelvic lymph node (LN) oligometastasis is a pattern of failure that is observed occasionally. Although radiotherapy may be useful for salvage therapy, the optimal prescription dose has not yet been clarified. This study assessed the efficacy of high-dose radiotherapy. Methods: Between 2008 and 2018, the medical records of 113 patients with 1–5 abdominal/pelvic LN oligometastases treated with definitive radiotherapy at 4 institutes were retrospectively analysed. The exclusion criteria were non-epithelial tumours, uncontrolled primary lesions, palliative intent, and re-irradiation. The prescription dose was evaluated by using the equivalent dose in 2 Gy fractions (EQD2); patients with EQD2 ≥60 Gy were the high-dose group. Kaplan-Meier analysis was used to evaluate the endpoints of overall survival (OS), local control (LC), and progression-free survival (PFS). Univariate log-rank and multivariate Cox proportional hazards model analyses were performed to clarify predictive factors for each endpoint. Toxicity rates were compared between the high-dose and low-dose groups. Results: The primary tumour sites included the colorectum (n = 28), uterine cervix (n = 27), endometrium (n = 15), and ovaries (n = 10). The 2-year OS, LC, and PFS rates were 63.1%, 59.7%, and 19.4%, respectively. On multivariate analyses, solitary oligometastasis, high-dose radiotherapy, and long disease-free interval were associated with significantly favourable OS (hazard ratio [HR]: 0.48, p = 0.02), LC (HR: 0.93, p < 0.001), and PFS (HR: 0.59, p = 0.01), respectively. Although high-dose radiotherapy did not significantly improve the 2-year OS of the entire cohort (74.8% vs. 52.7% in the high-dose vs. low-dose group; p = 0.08), it showed a significant difference on subgroup analysis for solitary oligometastasis (88.8% vs. 56.3%; p = 0.009). Late grade ≥3 toxicity included ileus in 7 cases (6%) and gastrointestinal bleeding in 4 (4%). There was no significant association between the irradiation dose and toxicity incidence. Conclusions: Salvage radiotherapy was feasible for oligometastasis of the abdominal/pelvic LNs. For solitary oligometastasis, the high-dose group showed favourable results considering LC and OS.

British Gynaecological Cancer Society (BGCS) uterine cancer guidelines: Recommendations for practice

“…[269] Other studies on patients with recurrent gynaecological cancers (including cervical cancers with central pelvic, pelvic sidewall or para-aortic recurrence only) identified tumour volume (>24-30 cm 3 ) being an independent adverse prognostic factor. [270,271] For bulky retroperitoneal nodal recurrences, surgical resection may be an effective treatment strategy.…”