Chapter 087. Gastrointestinal Tract Cancer (Part 5)

Gastric Adenocarcinoma: Treatment Complete surgical removal of the tumor with resection of adjacent lymph nodes offers the only chance for cure. However, this is possible in less than a third of patients. A subtotal gastrectomy is the treatment of choice for patients with distal carcinomas, while total or near-total gastrectomies are required for more proximal tumors. The inclusion of extended lymph node dissection in these procedures appears to confer an added risk for complications without enhancing survival. The prognosis following complete surgical resection depends on the degree of tumor penetration into the stomach wall and is adversely influenced by...
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Chapter 087. Gastrointestinal Tract Cancer (Part 5) Chapter 087. Gastrointestinal Tract Cancer (Part 5) Gastric Adenocarcinoma: Treatment Complete surgical removal of the tumor with resection of adjacent lymphnodes offers the only chance for cure. However, this is possible in less than a thirdof patients. A subtotal gastrectomy is the treatment of choice for patients withdistal carcinomas, while total or near-total gastrectomies are required for moreproximal tumors. The inclusion of extended lymph node dissection in theseprocedures appears to confer an added risk for complications without enhancingsurvival. The prognosis following complete surgical resection depends on thedegree of tumor penetration into the stomach wall and is adversely influenced byregional lymph node involvement, vascular invasion, and abnormal DNA content(i.e., aneuploidy), characteristics found in the vast majority of American patients.As a result, the probability of survival after 5 years for the 25–30% of patients ableto undergo complete resection is ~20% for distal tumors and have generally included cisplatin combined with either epirubicin and infusional5-FU or with irinotecan. Despite this encouraging response rate, completeremissions are uncommon, the partial responses are transient, and the overallinfluence of multidrug therapy on survival has been unclear. The use of adjuvantchemotherapy alone following the complete resection of a gastric cancer has onlyminimally improved survival. However, combination chemotherapy administeredbefore and after surgery (perioperative treatment) as well as postoperativechemotherapy combined with radiation therapy reduces the recurrence rate andprolongs survival. Primary Gastric Lymphoma Primary lymphoma of the stomach is relatively uncommon, accounting fora given case should not be interpreted as being conclusive, since superficialbiopsies may miss the deeper lymphoid infiltrate. The macroscopic pathology ofgastric lymphoma may also mimic adenocarcinoma, consisting of either a bulkyulcerated lesion localized in the corpus or antrum or a diffuse process spreadingthroughout the entire gastric submucosa and even extending into the duodenum.Microscopically, the vast majority of gastric lymphoid tumors are non-Hodgkinslymphomas of B cell origin; Hodgkins disease involving the stomach is extremelyuncommon. Histologically, these tumors may range from well-differentiated,superficial processes [mucosa-associated lymphoid tissue (MALT)] to high-grade,large-cell lymphomas. Like gastric adenocarcinoma, infection with H. pyloriincreases the risk for gastric lymphoma in general and MALT lymphomas inparticular. Gastric lymphomas spread initially to regional lymph nodes (often toWaldeyers ring) and may then disseminate. Gastric lymphomas are staged likeother lymphomas (Chap. 105). Primary Gastric Lymphoma: Treatment Primary gastric lymphoma is a far more treatable disease thanadenocarcinoma of the stomach, a fact that underscores the need for making thecorrect diagnosis. Antibiotic treatment to eradicate H. pylori infection has led toregression of about 75% of gastric MALT lymphomas and should be consideredbefore surgery, radiation therapy, or chemotherapy are undertaken in patientshaving such tumors. A lack of response to such antimicrobial treatment has beenlinked to a specific chromosomal abnormality, i.e., t(11;18). Responding patientsshould undergo periodic endoscopic surveillance because it remains unclearwhether the neoplastic clone is eliminated or merely suppressed, although theresponse to antimicrobial treatment is quite durable. Subtotal gastrectomy, usuallyfollowed by combination chemotherapy, has led to 5-year survival rates of 40–60% in patients with localized high-grade lymphomas. The need for a majorsurgical procedure has been questioned, particularly in patients with preoperativeradiographic evidence of nodal involvement, for whom chemotherapy [CHOP(cyclophosphamide, doxorubicin, vincristine, and prednisone)] plus rituximab iseffective therapy. A role for radiation therapy is not defined because mostrecurrences develop at distant sites.