Pocket Oncology (Pocket Notebook Series), 1st Ed.

APPENDIX AND SMALL BOWEL CARCINOMA

Jean K. Lee and Leonard Saltz

APPENDICEAL CARCINOMA*

Epidemiology and Classification

Appendiceal neoplasms are rare & usu. found incidentally; found in 1% of appendectomy specimens & comprise <1% of all intestinal neoplasms (∼0.12 cases/1000000)

Main histologic types:

Carcinoids

Adenoca

Adenocarcinoids (goblet cell CAs)

Cystadenomas

Cystadenoca

Epithelial tumors: Adenoca more common 1° malignancies of appendix; 3 subtypes include:

Mucinous adenoca (most frequent)

Intestinal-type

Signet ring cell adenoca (least frequent, SEER database, NCI)

Appendiceal adenoca biologically resembles colonic adenoca; signet ring cell form w/poor prognosis

Mucinous appendiceal tumors range from low-grade benign mucinous cystadenomas to high-grade invasive malignancies cystadenomas can develop into mucoceles & recur as disseminated peritoneal mucinous tumors → pseudomyxoma peritonei, mucinous implants in the peritoneum characteristic “jelly belly”; mucinous tumors have predilection for peritoneal dissemination

Rare mucinous cystadenoca identified by invasion through appendiceal wall or epithelial cells in peritoneal mucus

Clinical Presentation, Staging, and Prognosis

S/s:

Appendiceal adenoca often present as acute appendicitis

May also p/w abdominal pain, ascites, abdominal mass, & increasing abdominal girth

In adv cases peritoneal carcinomatosis & intestinal obstruction in pseudomyxoma peritonei

CT scan characteristics: Mucocele seen as well-defined mass usu. in the RLQ, adj to cecum; presence of intramural nodule suspicious for cystadenoca; characteristic peripheral location of tumor w/central displacement of small bowel in pseudomyxoma peritonei

Staging based on AJCC TMN staging for appendiceal CA

Prognosis: 5-y survival rates for appendiceal adenoca:

Stage I 81.1%

Stage II 52.6%

Stage III 32.9%

Stage IV 22.7% (SEER, 1973–2005)

Prognosis varies according to histologic type; mucinous & intestinal-type adenoca w/58% & 55% 5-y disease specific survival, respectively; signet ring cell CA w/worst prognosis (27%)

Management

Epithelial tumors of appendix:

Appendectomy for simple mucoceles, cystadenomas, some cystadenoca; important that the tumor does not rupture intraoperatively

Right hemicolectomy indicated for cystadenoca w/mesenteric involvement, complicated mucoceles w/terminal ileum/cecum involvement, cystadenoca, goblet cell

Adenoca:

Right hemicolectomy standard of care. Role of adjuvant chemotherapy unclear w/lack of prospective randomized trials. In general, adjuvant 5-FU-based chemotherapy recommended for pts w/node-positive intestinal type adenoca

Data extrapolated from studies for adjuvant chemotherapy for node-positive colon CA. In cases of intraperitoneal dissemination optimal tx unclear; surgical cytoreduction performed in selected pts

Benefit of systemic chemotherapy in adv met setting unclear due to lack of prospective trials. NCCN Guidelines do not exist for appendiceal adenoca & are currently based on systemic chemotherapy paradigms for CRC (5-FU & platinum drug; see Colon Cancer)

Pseudomyxoma peritonei: Recommend repeated surgical debulking for sx disease & is not curative; radical surgical cytoreduction of intra-abdominal & pelvic disease & more aggressive Rx w/IPHC used in some centers. However, this approach is not universally accepted as standard practice

Optimal tx of mucinous appendiceal adenoca unclear given lack of prospective studies; options include cytoreductive surgery, systemic chemotherapy, intraperitoneal chemotherapy including intraoperative HIPEC & EPIC