The Influence of “Omental Cake” Presence on the Completeness of Cytoreduction in Advanced-stage Ovarian Cancer

Discussion

Initially considered as a fatty apron which covers the small bowel by Hippocrates and Aristotle, the role of the omentum was studied for the first time in 1893 by Ross, who demonstrated its protective function for the abdominal organs (12-14). Two decades later, the role of omentum in limiting the inflammatory processes was intuited when studying the modifications which take place at this level in cases presenting acute abdominal pathologies such as gastric ulcer, appendicitis or bowel obstruction (15).

Defined as a multi-layer structure with peritoneal origin which extends from the stomach and transverse colon and which covers the small bowel, the greater omentum contains various amounts of lymph nodes as well as fatty tissue (16). This structure plays a crucial role in preventing the development of different pathological processes at the abdominal level; however, at a certain point this structure will be transformed from a natural barrier to a pattern of spread for malignant cells with various origins, leading to development of a tumoral mass. This transformation is frequently encountered in malignancies such as gastric, colonic or ovarian cancer and has been considered since long as a sign of poor outcomes (17, 18). When it comes to ovarian cancer, two essential observations regarding the role of omentum should be presented; the first is referred to the fact that cases in which omentum was retrieved at the time of primary surgery exhibited a better outcome and the second is referred to the fact that in cases in which ovarian cancer relapsed, the greater omentum was a frequently encountered site of relapse (19-21). In this respect, omentectomy has been routinely associated as part of debulking surgery for advanced-stage ovarian cancer (19); therefore, since 2012, infracolic omentectomy became part of the guidelines for treating ovarian cancer (22).

However, in certain cases tumor invasion of the omentum might be massive, leading to transformation of the greater omentum in a diffuse thickened, tumoral mass; in such cases the unanimously accepted notion is of omental cake and might be associated with poorer outcomes. Most often, the presence of omental cake is associated with extensive disease which might preclude the achievement of a complete cytoreduction.

An interesting study that investigated the influence of the presence of omental cake on the type of cytoreduction was conducted by Fagotti et al. in 2006 (23). The study included 61 patients diagnosed with advanced-stage ovarian cancer, submitted to laparoscopy in order to evaluate the feasibility of complete cytoreduction. The authors created a score which included the presence of omental cake, peritoneal carcinomatosis, diaphragmatic carcinomatosis, mesenteric, bowel, gastric infiltration and respectively the presence of liver metastases, each criteria being noted with an index of 2; this index was calculated during laparoscopy and therefore patients were submitted to debulking surgery. The rate of patients benefitting from optimal debulking (defined by the presence of residual volume smaller than 1 cm) was of 67.2% and was significantly influenced by the laparoscopic-based score; therefore, the chances of achieving optimal cytoreduction were significantly diminished in cases in which this score was higher than 8, the specificity and the positive predictive value of the method being of 100% (23). In this respect, the affirmation that the presence of omental cake significantly influences the risk of achieving an incomplete debulking proves to be a valid one. A more recent study conducted on this issue involved 279 patients submitted to cytoreductive surgery with curative intent; among these cases incomplete cytoreduction was significantly influenced by the presence of omental cake and diffuse peritoneal thickening (24). Similarly to these studies, in our case the presence of omental cake significantly diminished the chances to achieve complete debulking.

In order to achieve a better identification of patients who might present omental cake and might not benefit from complete cytoreduction, more recent studies came to propose new predictive scores based on preoperative investigations (25). Therefore, it seems that information given by computed tomography might play a crucial role. According to Kim's study, the presence of omental involvement extending to the stomach or spleen on the preoperative computed tomography in association with inguinal or pelvic lymph node involvement should be considered as predictive factors for suboptimal debulking; in this context the authors underlined the utility of administration of neoadjuvant therapy in such cases in order to increase the radicality of the surgical procedure. However, association of omental cake, large volumes of ascites and higher levels of CA125 were not significantly correlated with incomplete debulking. Moreover, the authors underlined the fact that the findings reported at computed tomography were closely correlated with those encountered intraoperatively (25).

As for the necessity of performing multiple visceral resections in such cases, this finding seems to be perfectly justified due to the close anatomical reports between the greater omentum and the digestive tract represented by transverse colon, greater gastric curvature and small bowel; furthermore, extension of the nodules of peritoneal carcinomatosis at the level of the other segments of the colon as well as the development of visceral peritoneal carcinomatosis explains why more extended digestive resections such as subtotal or even total colectomy might be needed in order to achieve compete cytoreduction (3-5, 19).