Background
Gastric carcinoma is the second most common GI-cancer with a poor overall prognosis. Surgical resection is the only curative treatment option in afflicted patients. Detrimentally, the overall resection rate is as low as 33%, and in less than 60% of these patients R0-resection is possible. At the time of diagnosis, half of patients suffer from advanced tumor disease making curative resection uncertain at best. The probability of lymph node metastasis rapidly increases with the depth of infiltration. Already patients with stage Ib tumors have a high likelihood of lymph node metastases and therefore have a high recurrence rate of up to 69%, even following curative surgery. Locoregional recurrence is most common (87%), but peritoneal and liver metastasis occur as well (13%). These data dramatically illustrate the importance of detecting gastric carcinoma at earlier stages.
The current survival rate across all tumor stages ranges between 40% and 50% and is still achieved primarily by curative surgical resection. Only patients with Ia-tumors have a reasonably good prognosis with a 5-year survival rate of 83%. The survival rates of patients with more advanced tumors quickly decreases to 69% in patients with Ib tumors, 43% in stage II, 28% in stage III and 8.7% in stage IV patients.
Perioperative chemotherapy was thought to improve this dire prognosis, especially in patients with advanced tumor stages (UICC Ib-III) by down-staging the tumor and increasing the rate of curative resection. Intraoperative radiation or adjuvant radio-/chemotherapy with various regimens do in fact successfully reduce locoregional recurrence, but fail to improve the long-term outcome.
Neoadjuvant chemotherapy (CTx) on the other hand is believed to reduce intraoperative tumor cell dissemination as well as occult micrometastases. Strategically, it is hoped that this may increase the curative resection rate and reduce locoregional recurrence, thus improving the prognosis of advanced gastric carcinoma.