Disseminated cancer cells in the peritoneal cavity: what can we do when we detect them?

A feasibility study of postoperative chemotherapy with S-1 and cisplatin (CDDP) for gastric carcinoma (CCOG0703)

BACKGROUND

The outcome of stage III gastric cancer patients treated by D2 dissection followed by adjuvant chemotherapy with S-1 remains unsatisfactory. Moreover, some patients with a preoperative diagnosis of stage II/III turn out to be stage IV after surgical exploration, and a standard postoperative treatment for this population has not been established.

METHODS

A feasibility study of postoperative S-1/cisplatin (CDDP) was performed with patients who underwent gastrectomy for what turned out to be a stage IV gastric cancer. The primary endpoint of the trial was the relative dose intensity during five courses of S-1/CDDP. Several criteria to skip, postpone, or reduce the dose had been predetermined.

RESULTS

Between 2007 and 2009, 31 patients were accrued, including 19 patients who were positive for peritoneal washing cytology, 6 with peritoneal seeding, 5 with metastasis to the paraaortic nodes, and 4 with other distant metastases. Only 7 patients completed five cycles as planned (median, two cycles). The median relative dose intensities of S-1 and CDDP were 37% and 40%, respectively. Causes of treatment failure were failure to fulfill criteria for starting a new course within 5 weeks of the last administration of S-1 in 7, patient refusal in 6, disease recurrence/progression in 4, need to reduce dose by two levels in 4, and two successive skips of CDDP in 3 patients. The median progression-free survival time of all patients was 363 days.

CONCLUSIONS

Although promising in the neoadjuvant and advanced/metastatic setting, S-1/CDDP is too toxic as a postgastrectomy treatment for Japanese patients.

Positive peritoneal washing cytology in multiple cavities can predict poor prognosis of advanced gastric cancer patients

BACKGROUND

Positive peritoneal washing cytology (PWC) has been reported to be a poor prognostic factor for gastric cancer. Japanese gastric cancer classifications recommend PWC in Douglas' pouch for advanced gastric cancer. However, the sensitivity of PWC is relatively low. The goal of this study was to investigate whether PWC in multiple cavities increases its sensitivity to predict prognosis.

METHODS

Between January 1996 and December 2006, a series of 992 patients with gastric cancer underwent D2 gastrectomy with intraoperative PWC. Of the 992 patients, 62 patients had positive PWC. PWC was conducted in four cavities (left subphrenic cavity, right subhepatic cavity, Douglas' pouch, and inside the omental bursa). The 62 patients were retrospectively analyzed for their background and survival.

RESULTS

Eleven (17.7%) patients had negative PWC in Douglas' pouch but were positive in the other cavities. The 62 patients were classified into two groups according to the number of positive PWC cavities: 20 patients with one or two and 42 patients with three or four positive PWC cavities. No significant difference in clinicopathological features was observed between these two groups. However, the overall and progression-free survival rates of patients with one or two positive PWC cavities were significantly higher than those for patients with three or more positive PWC cavities.

CONCLUSION

PWC in multiple cavities was more sensitive than only in one cavity. The number of positive cavities may indicate the grade of tumor spread in the peritoneum and predict the prognosis of patients with positive PWC.