Online Program

323232
Age as a prognostic factor of stage IV melanoma: A competing risks analysis using proportional subdistribution hazards regression


Tuesday, November 3, 2015 : 12:30 p.m. - 12:48 p.m.

Jessica Hoag, MPH, Department of Community Medicine and Health Care, University of Connecticut Health Center, Farmington, CT
Upendra Hegde, MD, Department of Medicine, University of Connecticut Health Center, Farmington, CT
Rebecca Zweifler, BA, University of Connecticut Health Center, West Hartford, CT
Marianne Berwick, PhD, MPH, Department of Internal Medicine and Department of Dermatology, The University of New Mexico, Albuquerque, NM
Helen Swede, PhD, Department of Community Medicine and Health Care, University of Connecticut Health Center, Farmington, CT
background: Survival from cutaneous metastatic melanoma (MM) is substantially heterogeneous as reflected in three distinct AJCC TNM subtypes (M1a, M1b, M1c), which is taken into consideration during treatment decision-making.  It remains unknown, however, if older patients also experience variation in survival given an overall higher risk of mortality.

objective: Among MM patients, compare the effect of age on overall, melanoma-specific, and other-cause morality using a competing risks analysis.

methods: The study sample (n= 1,908) of MM patients was derived from the population-based NCI Surveillance, Epidemiology and End Results program. Patients were diagnosed from 2005 to 2009 with follow-up to 2011.  Melanoma-specific and non-melanoma mortality risk were estimated using proportional subdistribution hazards ratios (SHR), modeled directly on cumulative incidence functions which treats events occurring prior to the primary endpoint as informative, and not wholly censored.  Age at diagnosis was dichotomized into younger (< 65 years) and older (≥ 65 years) groups.

results: Median survival time among patients alive at the close of the study was 41 months. Older age was associated with an increase in non-melanoma mortality (SHR: 2.01, 95% CI: 1.61-2.51) compared to younger patients among all MM patients, which also was observed for each M1 subtype. Although a protective effect for older age was suggested for melanoma-specific mortality (SHR: 0.84, 95% CI: 0.74-0.94), this is likely due to the association of older age with non-melanoma death, and was not observed within M1 subtypes. When overall mortality was considered as the endpoint, risk of death did not vary by age in the total sample.

conclusion: Proportional subdistribution hazards regression provides a more precise assessment of risk of death among older MM patients given increased risk of death from all causes. Older age was associated with worse non-melanoma mortality within each M1 subtype, which could benefit clinical decision-making.

Learning Areas:

Epidemiology
Public health or related research

Learning Objectives:
Compare cumulative incidence functions for overall, stage IV melanoma-specific, and competing cause mortality. Demonstrate the utility of a proportional subdistribution hazards regression modeled directly on a cumulative incidence function to allow for estimation of the effect of age and other covariates on melanoma-specific mortality.

Keyword(s): Cancer, Biostatistics

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am a 3rd-yr PhD student in public health at the University of Connecticut Health Center, with a research focus on cancer epidemiology and biostatistics. The present study has been conducted under supervision of Helen Swede, PhD and Upendra Hegde, MD. Dr. Swede is a cancer epidemiologist and my faculty advisor. Dr. Hegde is a board certified medical oncologist who has published in multiple peer-reviewed journals on the topic of metastatic melanoma in older patients.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.