Cohort studies of etiology and survival after cancer: the unique needs for uninterrupted funding

The Impact of the Nurses' Health Study on Population Health: Prevention, Translation, and Control

OBJECTIVES

To summarize the overall impact of the Nurses' Health Study (NHS) over the past 40 years on the health of populations through its contributions on prevention, translation, and control.

METHODS

We performed a narrative review of the findings of the NHS, NHS II, and NHS3 between 1976 and 2016.

RESULTS

The NHS has generated significant findings about the associations between (1) smoking and type 2 diabetes, cardiovascular diseases, colorectal and pancreatic cancer, psoriasis, multiple sclerosis, and eye diseases; (2) physical activity and cardiovascular diseases, breast cancer, psoriasis, and neurodegeneration; (3) obesity and cardiovascular diseases, numerous cancer sites, psoriasis, multiple sclerosis, kidney stones, and eye diseases; (4) oral contraceptives and cardiovascular disease, melanoma, and breast, colorectal, and ovarian cancer; (5) hormone therapy and cardiovascular diseases, breast and endometrial cancer, and neurodegeneration; (6) endogenous hormones and breast cancer; (7) dietary factors and type 2 diabetes, cardiovascular diseases, breast and pancreatic cancer, non-Hodgkin's lymphoma, neurodegeneration, multiple sclerosis, kidney stones, and eye diseases; and (8) sleep and shift work and chronic diseases.

CONCLUSIONS

The NHS findings have influenced public health policy and practice both locally and globally to improve women's health.

Preventability of cancer: the relative contributions of biologic and social and physical environmental determinants of cancer mortality

Whereas models of cancer disparities and variation in cancer burden within population groups now specify multiple levels of action from biologic processes to individual risk factors and social and physical contextual factors, approaches to estimating the preventable proportion of cancer use more traditional direct models often from single exposures to cancer at specific organ sites. These approaches are reviewed, and the strengths and limitations are presented. The need for additional multilevel data and approaches to estimation of preventability are identified. International or regional variation in cancer may offer the most integrated exposure assessment over the life course. For the four leading cancers, which account for 50% of incidence and mortality, biologic, social, and physical environments play differing roles in etiology and potential prevention. Better understanding of the interactions and contributions across these levels will help refine prevention strategies.

Ensuring long-term sustainability of existing cohorts remains the highest priority to inform cancer prevention and control

The case for continued follow-up of existing cohorts arises from the key attributes of cohorts that are already meeting the goals proposed by Potter for the creation of a new cohort. These attributes include the basic nature of ongoing cohorts in that they are, by design, hypothesis-driven and must adapt to emerging technologies over time. Importantly, cohort investigators must identify and address gaps in knowledge that will inform public health strategies and clinical practices. Above all, cohorts must capitalize on their unique features to address public health priorities and inform our prevention strategies. Continued follow-up adds substantial return on investment to guide cancer prevention.