Defining patients with a high risk of developing peritoneal carcinomatosis after curative surgery

The objective of this study was to identify risk factors predictive for developing peritoneal carcinomatosis (PC) after curative surgery for colorectal cancer (CRC). The data show three situations that could result in a real risk of recurrent PC: synchronous PC, synchronous isolated ovarian metastases and a perforated primary tumor. There is however not enough scientific evidence regarding factors that predict PC.
 

Peritoneal carcinomatosis (PC – cancer seeding of the peritoneum) after curative surgery for CRC occurs in nearly 10% of all patients. With older chemotherapy regimens, the survival does not exceed 6 months and with newer drugs it is usually less than 24 months. However, by combining cytoreductive surgery (surgical removal of part of a cancerous tumor which cannot be completely taken out) with hyperthermic  intraperitoneal chemotherapy (HIPEC – high temperature drugs applied inside the abdomen) the 5-year survival rate can reach 42%.

The current noninvasive assessments are not reliable in detecting peritoneal carcinomatosis early on. The best method remains a "second look" surgery, but this option can only be proposed to individuals with a higher risk of cancer spread.

This paper reports results selected from 16 studies published between 1940 and 2011. Several factors associated with curative surgery of the primary tumor were predictive of future peritoneal recurrences:

1) Synchronous peritoneal carcinomatosis was discovered during curative surgery in almost 5% of patients. A study showed that 54 to 75% developed peritoneal recurrences even if the PC was completely removed at the time of the initial surgery.

2) Synchronous ovarian metastases (spread of cancer to the ovaries) were found in about 0.8 to 7.4 % of all colorectal cancers. The results of two different studies showed that ovarian metastases were associated in 29 to 72% of the cases with PC. PC also recurred in 56 to 62% of cases with ovarian metastases.

3) Perforated (ruptured) primary tumors had a frequency that was hard to determine accurately. The overall rate of perforation was found to be between 1 and 8%. Recurrent PC after tumor perforation was assessed in 4 studies and ranged between 14 to 54% of the patients.

4) Histological subtype (type of cancerous cells) was mucinous adenocarcinoma (cancer from the epithelial cells that produces mucus) in most cases. With this type of cancer, recurrent PC was found in 11 to 36% of the patients.

5) Based on an analysis of 9 studies, 15% of patients had cancerous cells detected through various techniques (or positive cytology).  Recurrent PC was found in 9 to 36% of these patients.

6) The primary colorectal tumor invaded nearby organs in 16 % of the cases. Between 8 and 17 % of these patients eventually developed peritoneal recurrences. 

This study underlines the lack of strong evidence regarding predictive factors of recurrent PC. Only three of the 6 above mentioned factors are associated with a higher risk of recurrent PC: synchronous PC, synchronous isolated ovarian metastases and a perforated primary tumor.