Alexander,M.D. Melamed, M.D., M.P.H.

Physician Investigator (Cl)
Obstetrics & Gynecology, Mass General Research Institute
Member of the Faculty of Obstetrics, Gynecology and Reproductive Biology
Obstetrics Gynecology & Repro. Bio. , Harvard Medical School
Obstetrics & Gynecology, Massachusetts General Hospital
MPH University of Southern California 2008
MD USC Keck School of Medicine 2012
cancer care; causal inference; cervical cancer; gynecological cancers; natrual experiments; ovarian cancer; quasi-experimental methods; surgical oncology; surgical procedures minimally invasive; uterine cancer; women's health services

Classical epidemiologic study designs, like cohort and case-control studies, are very powerful. However, the use of these designs in investigations of the effects of cancer treatments on patient outcomes is not always sensible.

The treatment that a cancer patient receives is influenced by prediagnosis characteristics, disease factors, and provider attributes that may also affect the outcomes being studied. When enough confounders have been measured, it may be possible to accurately estimate causal associations between treatments and outcomes using a classical epidemiological approach. Unfortunately, it is common that the available data is missing information about important confounders. Unmeasured (and unmeasurable) confounding is a central threat to the validity of causal claims about cancer treatments when such claims are based on analyses of observational data.

In my observational research, I use analytical approaches that can, sometimes, overcome unmeasured confounding by identifying natural experiments in cancer care delivery. Specifically, I am interested in how focusing on the variability of treatments across time, space, and provider can help to estimate treatment effects, and overcome treatment selection bias.

I use methods like difference-in-differences, instrumental variables analysis, interrupted time series, and regression discontinuity designs to generate evidence about the causal effects of cancer treatments on survival, treatment-related toxicity, and medical costs. As a surgeon, I am especially interested in studying the effect of surgical care on cancer outcomes. 

By generating credible clinical evidence from observational cancer data, I seek to help patients and oncologists make better and more informed treatment decisions.