For patients with metastatic renal cell carcinoma (RCC), the average 5-year survival from time of diagnosis is low — 12% — but that number does not take into account whether a patient had already survived for a certain number of years. A metric that does factor in current survivorship is conditional survival, and may more accurately assess prognosis than traditional survival and even bring optimism to metastatic RCC patients, according to the findings of a large population-based cohort study recently published in Frontiers in Oncology.

“Prognosis is important for patients so that they can plan their lives,” said Pavlos Msaouel, MD, PhD, assistant professor, department of genitourinary medical oncology, division of cancer medicine, The University of Texas MD Anderson Cancer Center, Houston, during an interview with Cancer Therapy Advisor. “Obviously those numbers [for prognosis] will change a year later if things have gone favorably for a patient,” explained Dr Msaouel, who was not involved in the study. “That’s what conditional survival is.”

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Conditional survival has been assessed across many cancer types — pancreatic, colon, head and neck, and so on — and is defined as the probability of surviving a certain number of additional years once a patient has already survived a specified number.2 

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“In the overall sense, it is a different way to look at survival and can be informative for some doctors and patients, and is not certainly a common way we look at survival,” said Kai Tsao, MD, Medical Director of the Ruttenberg Treatment Center at Mount Sinai’s Tisch Cancer Institute, during an interview with Cancer Therapy Advisor. He was not involved in the study. “But it’s an interesting and unique outlook on survival in cancer,” Dr Tsao added.

Studies have proposed using conditional survival as a shared decision-making tool during counseling sessions with patients, and some investigators have even created online tools for this purpose. For example, Charles Thomas, Jr., MD, professor and chair, department of radiation medicine, Oregon Health & Science University (OHSU) Knight Cancer Institute, Portland, told Cancer Therapy Advisor that he and colleagues have developed several clinical prediction calculators, which are available online through OHSU. Some of the tools include conditional survival in the calculation, and plans are under way to create more nomograms. 

The current calculators online, however, are static — that is, they are based on data that may be from a population-based study conducted using data from the Surveillance, Epidemiology, and End Results (SEER) database several years ago. Ideally, Dr Thomas said, the tools would autopopulate with the latest data from the SEER database. “That’s something we’re working on,” he said.

Although the current study with metastatic RCC patients is newly published, the data are, in a way, similarly outdated because of the patient population used and the considerable progress that has been made in this treatment space since when the study first began. Data on nearly 90,000 patients were extracted from the SEER database, but the problem is the time period was 2004 to 2014.

“Most of the currently used therapies for metastatic stage IV kidney cancer were approved after that [time period],” said Dr Msaouel. For example, the first immunotherapeutic for patients with advanced RCC, nivolumab, was approved in 2015.3 What this means, he explained, is that the absolute numbers reported in the current study are not going to be necessarily relevant because oncologists now have a “very different” therapeutic armamentarium.

The study also used the Fudan University Shanghai Cancer Center (FUCSS) database to enroll more than 2000 patients who were treated through 2018, but another problem, Dr Msaouel said, is that only approximately 200 patients with stage IV disease were included, and the treatments that were received were not disclosed.  

Another limitation of the study that hinders its applicability to today’s patient is that patient data were not stratified by the IMDC (International Metastatic RCC Database Consortium) Risk Score — that is, favorable, intermediate, and poor risk — and this score is often used to determine a patient’s prognosis. “It’s not like every patient with clear cell kidney cancer stage IV metastatic disease has the same probability of surviving for 5 years,” Dr Msaouel said. “It all depends on certain risk factors, and the IMDC risk factor is an excellent way of stratifying.”