An Overview of Adenocarcinoma of the Small Intestine

Neugut and colleagues have compiled a very comprehensive, thoughtfuldescription of the incidence, epidemiology, etiology, clinical presentation,and treatment of small bowel malignancies. This is a very unusual tumorthat few clinicians will encounter during their careers, and fewer stillwill diagnose preoperatively.

I certainly concur with the authors' statement that surgical interventionprovides the only hope of cure for these patients. I disagree, however,that small bowel tumors are unresectable when there are metastases to regionallymph nodes. In general, patients with small intestinal adenocarcinomasare managed with aggressive regional mesenteric lymphadenectomy, even whenthe nodes are clinically negative. Survival among patients with positivenodes is certainly seen in this disease. The local criteria of unresectabilityinclude involvement of central, as opposed to peripheral, mesenteric vessels.

Role of Radiation Therapy

With regard to the role of radiation therapy, one of the reasons thatit is inappropriate relates to the mobility of the small bowel; this mobilitymakes it exceedingly difficult to define a treatment field. In theory,what is appealing about intraoperative radiation therapy is its abilityto define a field at risk for locoregional recurrence while at the sametime excluding adjacent viscera from that field.

Finally, with respect to the appropriate treatment of duodenal adenocarcinoma,it is extremely difficult in small retrospective series to separate theimpact of treatment from that of patient selection. One would expect thatpatients with unresectable disease treated with chemotherapy and/or radiationtherapy would have more advanced disease, and thus, would not do as wellas those who are potentially resectable with pancreaticoduodenectomy. Iagree with the authors that the extent of surgical resection is not a uniformpredictor of improved outcome.

The authors are to be commended for very succinctly summarizing thecurrent state of knowledge about this unusual tumor. They have emphasizedthe frustration we all feel in dealing with unusual malignancies: Giventhe nearly insurmountable difficulties in mounting large cooperative prospectivetrials, we are unlikely to know much more about the biology or treatmentof there "orphan diseases" 10 years from now.