Neugut and colleagues have compiled a very comprehensive, thoughtful
description of the incidence, epidemiology, etiology, clinical presentation,
and treatment of small bowel malignancies. This is a very unusual tumor
that few clinicians will encounter during their careers, and fewer still
will diagnose preoperatively.
I certainly concur with the authors' statement that surgical intervention
provides the only hope of cure for these patients. I disagree, however,
that small bowel tumors are unresectable when there are metastases to regional
lymph nodes. In general, patients with small intestinal adenocarcinomas
are managed with aggressive regional mesenteric lymphadenectomy, even when
the nodes are clinically negative. Survival among patients with positive
nodes is certainly seen in this disease. The local criteria of unresectability
include 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 that
it is inappropriate relates to the mobility of the small bowel; this mobility
makes it exceedingly difficult to define a treatment field. In theory,
what is appealing about intraoperative radiation therapy is its ability
to define a field at risk for locoregional recurrence while at the same
time 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 the
impact of treatment from that of patient selection. One would expect that
patients with unresectable disease treated with chemotherapy and/or radiation
therapy would have more advanced disease, and thus, would not do as well
as those who are potentially resectable with pancreaticoduodenectomy. I
agree with the authors that the extent of surgical resection is not a uniform
predictor of improved outcome.
The authors are to be commended for very succinctly summarizing the
current state of knowledge about this unusual tumor. They have emphasized
the frustration we all feel in dealing with unusual malignancies: Given
the nearly insurmountable difficulties in mounting large cooperative prospective
trials, we are unlikely to know much more about the biology or treatment
of there "orphan diseases" 10 years from now.