Relative survival for ovarian cancer improved over three decades

1. Survival for all stages of ovarian cancer improved significantly from 1975 to 2011 even after accounting for general advances in medical care.

2. Compared to 1975, women diagnosed with ovarian cancer in 2006 were roughly 50 percent less likely to die from their cancer.

Evidence Rating Level: 2 (Good)

Study Rundown: In 2015, approximately 21 290 American women will receive a new diagnosis of ovarian cancer and 14 180 will die from the disease. But a cancer that once was seen as a death sentence is now treatable. Thanks to tremendous advancements in scientific research, we now understand the value of debulking surgeries to remove tumor in advanced stage disease, the benefit of platinum chemotherapeutic agents and novel methods of medication delivery, such as intraperitoneal chemotherapy. Despite these advances, determining whether advances in treatment translate to population-level improvements in survival is difficult because improvements in medical care have also translated to prolonged life expectancy overall. In this study, researchers attempted to address this challenge by using relative survival—the ratio of survival for cancer patients to the expected survival of a comparable group from the general population.

According to data from a large national cancer database, relative survival for ovarian cancer has improved significantly over the past 3 decades, regardless of tumor stage.  Compared to 1975, women diagnosed with breast cancer in 2006 were roughly 50 percent less likely to die from their cancer. Strengths of this study include the large, nationally representative sample and accounting for advances in general medical care. One significant limitation was that staging criteria have changed over the years so some women may have been misclassified. Future studies that classify survival based on treatment type will further add to our understanding of the impact of advancements in ovarian cancer treatment.

Click to read the study in Obstetrics & Gynecology

Relevant Reading: Improved survival time: what can survival cure models tell us about population-based survival improvements in late-stage colorectal, ovarian, and testicular cancer?

In-Depth [retrospective cohort]: Women diagnosed with ovarian cancer from 1975 to 2011               (n = 42 932) were identified in the National Cancer Institute’s Surveillance, Epidemiology, and End Results database. Relative survival was estimated by comparing observed survival after cancer diagnosis with expected survival of a comparable group from the general population; excess mortality was the mortality rate above baseline in the general population. Mortality was compared for different time periods using hazard ratios.

For women with stage I ovarian cancer, excess mortality in 2006 was nearly half that in 1975   (HR = 0.51, 95%CI 0.41-0.63). Reduction in excess mortality remained significant when compared to 1980 and 1985. For women with stage III-IV cancer, excess mortality was lower in 2006 compared with all other years of study (relative to 1975, HR = 0.49, 95%CI 0.44-0.55; relative to 2000, HR = 0.93, 95%CI 0.87-0.99)

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