An estimated 1% (0.9%1.4%) of all appendectomy specimens contain a neoplasm. The majority of appendiceal tumors are carcinoids, while the remaining 10% to 20% are mucinous cyst adenocarcinoma, adenocarcinoma, lymphosarcoma, paraganglioma, and granular-cell tumors. As expected, most present as acute appendicitis, and in some 40% of cases, the diagnosis is made after appendectomy
|If a mass in the appendix is
encountered incidentally during the course of abdominal surgery, an appendectomy is
performed with frozen-section analysis of the mass. Most masses prove to be benign
mucoceles or very small carcinoids. When carcinoid tumors of the appendix are small (<1
cm in diameter), they may be treated adequately by standard appendectomy. If they are
greater than 2 cm in size, the patient should have a right hemicolectomy.
Treatment of appendiceal adenocarcinoma is a right hemicolectomy. Mucinous cystadenocarcinoma can be very difficult to manage.Treatment should be a right hemicolectomy and debulking of peritoneal implants.
Currently, the best results treating mucinous cyst-adenocarcinoma appear to be obtained with an aggressive combination of cytoreductive surgery, perioperative intraperiotneal chemohyperthermia, and early postoperative intraperitoneal chemotherapy. These measures could provide 5-year and 10-year survival rates as high as 80% and 60%, respectively. If debulking is incomplete, the survival rates are markedly reduced to only 20% and 0%, respectively, and long-term survival cannot be achieved. This tumor can be indolent in its course, and patients commonly have multiple debulking surgeries before ultimately succumbing to their disease.
see Cancer Net on Small Bowel Cancer or GI Carcinoid, online review article.
Primary malignant neoplasms
of the appendix
|Cancer of the appendix is an
uncommon disease that is rarely suspected rarely before surgery. Although several case
series of these tumors have been published, little research has been anchored in
population-based data on cancer of the appendix.
This analysis included all actively followed cases of appendiceal neoplasms reported to the National Cancer Institute's Surveillance, Epidemiology and End-Results (SEER) program between 1973 and 1998. Tumors were classified as colonic type adenocarcinoma, mucinous adenocarcinoma, signet ring cell carcinoma, goblet cell carcinoid, and malignant carcinoid (SEER only collects data on carcinoids specifically classified as malignant). We compared incidence, overall survival and survival rates by extent of disease at diagnosis.
From 1973 to 1998, 2117 primary malignant tumors of the appendix were reported to the SEER program. Adenocarcinomas were more likely to be excluded due to a previous diagnosis of malignancy (9% vs. 3-4% for the other histologies). No other differences in proportions of cases excluded were identified. There were 1689 cases eligible for inclusion in the study, 1645 of which were analyzed for the five most common histologic tumor types.
The age-adjusted incidence of appendiceal malignancies in the population represented by the SEER program was 0.12 cases per 1,000,000 people per year (crude incidence 0.12 cases per 1,000,000 people per year). No temporal trends in incidence were noted over the 26-year period. Table 1 shows patient characteristics for 1645 tumors in each of the five most common histologic types. Mucinous adenocarcinoma was the most frequent diagnosis, with 613 cases (37% of total). After controlling for age and extent of disease at diagnosis, the overall survival rate for patients diagnosed between 1983 and 1997 (n = 1061) was significantly worse for those with signet ring cell carcinoma than for those with any other tumor type (P < 0.01). In addition, overall survival rates were better for patients with malignant carcinoid (P = 0.01). Except for signet ring cell carcinoma and malignant carcinoid, histology did not have a significant impact on survival when age and extent of disease at the time of diagnosis were taken into account. Even though the unadjusted data suggest that a difference in survival does exist among the other tumor types, much of the difference in these data is explained by the degree of disease spread that is present when the tumors are discovered. Survival analysis by extent of disease limited the number of cases that were analyzed because detailed data on tumor spread were not collected before 1983. Therefore, the subsets within each group were small (Table 1). Future analyses of population-based data that include more cases may detect differences in survival between the other histologies. Alternatively, no other differences in survival may be present between the histologies.
The data analyzed for this population-based study confirm many of the findings reported from smaller case series of appendiceal malignancies. As suggested by other authors, the overall biologic behavior of goblet cell carcinoids in our series was intermediate between that of adenocarcinomas and carcinoid tumors in terms of age at diagnosis, extent of disease spread at diagnosis, and number of cases with lymph node involvement.
The contrast between mucinous adenocarcinoma and the so-called colonic type adenocarcinoma of the appendix has been given much consideration. The tumors are separate entities and the survival for patients with mucinous adenocarcinoma is better than that of people with the nonmucinous variety in two studies and worse in one. In our study, the hazards of death were equivalent for mucinous adenocarcinoma and colonic type adenocarcinoma. Although no differences in survival were evident, the differences in gender ratio and affected ethnicities support the notion that mucinous adenocarcinoma and colonic type adenocarcinoma are two distinct morphologies.
Primary signet ring cell carcinoma of the appendix is an exceedingly rare entity, and little information on the distinct characteristics of this tumor has been published. Like signet ring cell carcinomas of the stomach and colon, people with signet ring cell carcinoma of the appendix in this study had greater tumor extension at the time of diagnosis. Survival for patients with this type of tumor in the appendix is significantly worse than for patients with other tumor histologies. Moreover, the signet ring cell morphology itself did adversely affect survival even after disease extent and age were taken into account. Signet ring cell carcinoma is likewise a distinct tumor type in the appendix that should be considered separately from other carcinomas, especially because of its poor prognosis.
As has been described for carcinoid tumors in general, malignant carcinoids in this analysis were more common in women, had a younger average age at diagnosis, and had a better overall survival than all other histologic types of appendiceal tumors. Malignant carcinoid was the only other histology that had an impact on survival independent of age and extent of disease at time of diagnosis.
The data used for this study were collected from many sites around the United States and include diagnoses from hundreds of pathologists. Because of the way in which the data were collected, there are no effective means of establishing the reliability of the tissue diagnoses. Some of the diagnoses submitted to the SEER program may be incorrect, which could impact the reliability of our results. Our findings from this large-scale analysis confirm many of the findings already reported in the literature about appendiceal cancers. Even though our conclusions are limited by the observational nature of this study, these data may serve as a basis for comparison for future studies.
This study is the most extensive comparison of tumors of the appendix by histology published to date. The use of population-based data enhances the generalizability of the findings by including cases reported from a variety of institutions within a defined population. Surveillance data offer a statistically robust yet systematic view of appendiceal cancer, revealing information about the relative importance of histology and extent of disease that can help physicians and their patients to understand the implications of the diagnosis.
Treatment of peritoneal carcinomatosis from adenocarcinoid of appendiceal origin.
Mahteme H, Sugarbaker PH. Br J Surg. 2004 Sep;91(9):1168-73.
Department of Surgical Sciences, University Hospital of Uppsala, Sweden. Haile.Mahteme@Surgsci.uu.se
BACKGROUND: Mucinous peritoneal carcinomatosis arising from appendiceal adenocarcinoid is uncommon and treatment options have been poorly defined. This study examined the effect of combined cytoreductive surgery and intraperitoneal chemotherapy on survival in these patients. METHODS: Of 810 patients with peritoneal malignancy of appendiceal origin treated by cytoreductive surgery and intraperitoneal chemotherapy, 22 patients (mean age 45 years; 17 women) had adenocarcinoid. RESULTS: The overall median survival was 18.5 (range 3.2-95.1) months, with 2- and 5-year survival rates of 39 and 25 per cent respectively. Survival after combined surgery and chemotherapy depended on the Peritoneal Cancer Index (P = 0.008) and the extent of cytoreduction (P = 0.007). CONCLUSION: Peritoneal carcinomatosis from adenocarcinoid of appendiceal origin is as invasive as peritoneal surface malignancy from colorectal adenocarcinoma. Patients in whom complete or near-complete surgical removal is possible should be considered for cytoreduction in combination with intraperitoneal chemotherapy.