We hereby offer one of the first studies evaluating residual disease in peritoneal scars in patients treated by CRS ± HIPEC for ovarian cancer peritoneal metastases. We observed that around 51% of patients had microscopic residual disease in resected peritoneal scar-like lesions. The presence of positive peritoneal scar-like lesions were significantly associated with worse DFS on univariate analysis, 17 months for positive versus 29 months for negative PST.
Given the need for new prognostic factors to optimize PMOC patients’ selection and management, every clinical, histopathological and anatomical aspect, capable of enhancing the outcome of curative-intent CRS, should to be further explored.
PM from OC origin have a less aggressive behavior compared to those from colorectal or gastric origin, reason why patients with a relatively higher PCI are still eligible for surgery (12, 13). This warrants a higher rate of gastrointestinal resections, splenectomies and peritonectomies in PMOC patients compared to others. Platine-based chemotherapy and complete cytoreductive surgery, upfront or interval, remain the pillars of treatment in patients with PMOC (4, 14). Major prognostic factors remain the radicality of the CRS, PCI score, tumor histology and platinum-sensitivity, along with ascites and certain molecular expressions in ongoing investigations (15–17). This is corroborated by our study, reporting poorly differentiated tumors, advanced FIGO stage and high PCI score as independent prognostic factors in patients with PMOC.
Very few studies focused on the possible role of residual tumoral cells in peritoneal scar-like tissue (2, 10, 18). Recently, we have reported the potential role of ICG-FI in detecting residual tumoral disease in peritoneal scars (10). Despite the fact that ICG-FI was able to detect tumoral cells with a sensitivity of 73%, the reported specificity was low (57%).
The present study was aiming to analyze the rate and positivity of residual peritoneal scar-like tissue at pathology. It shows that benign-looking positive PST predict a worse median DFS (17 versus 29 months) on univariate analysis. However, it was not significant on multivariate analysis. Furthermore, we were not able to determine predictive factors for these PST positivity, especially when considering the group of patients with NACT versus those who did not take any neoadjuvant treatment. PST presence and positivity was not related to whether the patients received or not any type of NACT. This raises the question on whether PST should be systematically resected during CRS. At this stage, we still are unable to answer this question, and further studies on the effect of removing these PST are warranted.
Our study has numerous weaknesses and biases, starting with its retrospective design. In practice, the results of this study are based on our surgical attitude tending towards systematic resection or electrofulguration of all PST. However, some patients in the early stages of the study period were not operated while following this strategy. Therefore, it is possible that the rate of PST is still underestimated. This could also explain the absence of significant results for positive PST at multivariate analysis, given that a subgroup of patients is still harboring positive scar-like tissue. In addition, an operator-dependent bias is also present, given that visual and tactile evaluations were performed by the surgeon and his fellow. However, we tended to categorize lesions as “PST” using a set of morphological characteristics devised by the oncologic surgeons.
Still the results reported hereby, could constitute a modest foundation for further investigations in prospective studies. Moreover, the use of specific FI guided surgery in the future, should help the surgeons in detecting residual disease on a molecular level.