Date of Award

Spring 5-12-2017

Degree Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

Public Health

First Advisor

Dora Il'yasova

Second Advisor

Shishir Maithel

Third Advisor

Cecilia Ethun

Abstract

BACKGROUND

Most gallbladder cancers (GBC) are discovered incidentally after routine cholecystectomy. The relationship between the method of diagnosis and disease stage, treatment, and prognosis are not known.

METHODS

Patients with GBC who underwent resection at 10 institutions from 2000-2015 were included. Patients diagnosed incidentally (IGBC) and non-incidentally (non-IGBC) were compared. Primary outcome was overall survival (OS).

RESULTS

Of 445 patients with GBC, 266 (60%) were IGBC and 179 (40%) were non-IGBC. Compared to IGBC, non-IGBC patients were more likely to have R2 (macroscopic residual disease) resections (43 vs. 19%; p<0.001), advanced tumor (T) stage (T3/T4: 70 vs. 40%; p<0.001), high grade tumors (50 vs. 31%; p<0.001), lymphovascular invasion (LVI: 64 vs. 45%; p=0.01), and positive lymph nodes (LN: 60 vs. 43%; p=0.009). Receipt of adjuvant chemotherapy was similar between the groups (49 vs. 49%). Non-IGBC was associated with worse median OS compared to IGBC (17 vs. 32 months, p<0.001), which persisted among Stage III patients (12 vs. 29 months; p<0.001), but not Stages I, II or IV. After adjustment of other adverse pathologic factors (grade, T-stage, LVI, margin, LN), adjuvant chemotherapy was associated with improved OS only in Stage III IGBC but not in non-IGBC.

CONCLUSION

Compared to incidental discovery, non-incidental gallbladder cancer is associated with reduced overall survival, which is most evident in Stage III disease. Despite being well-matched for other adverse pathologic factors, adjuvant chemotherapy was associated with improved survival only in Stage III patients with incidentally discovered cancer. This underscores the importance of method of diagnosis in gallbladder cancer and suggests that these two groups may represent a distinct biology of disease, and the same treatment paradigm may not be appropriate.

Available for download on Friday, April 26, 2019

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