The survival of chronic lymphocytic leukemia (CLL) patients has steadily improved since the approval of new targeted therapies for first-line treatment and relapsed disease. The UACC team performed an analysis from the National Cancer Institutes, Survival, Epidemiology, and End Results (SEER) database. The team looked at data from 1973 to 2017 to explore both the trend of survival and the effect on CLL patient survival of the advanced targeted therapies. Unfortunately, the public release of SEER data tends to lag by about three years (2018 data was made available in April 2021).

To evaluate CLL Patient Survival, McBride’s team extracted data using SEER*Stat software. The SEER*Stat statistical software provides a convenient, intuitive mechanism for analyzing SEER and other cancer-related databases. It is a powerful PC tool to view individual cancer records and produce statistics for studying the impact of cancer on a population. They used data from all patients 15 years or older with a primary diagnosis of CLL with or without subsequent cancers.

A “period analysis” was done to estimate the five and ten-year relative survival rates for patients diagnosed (dx) during different calendar periods from 1985 to 2017. Long-term survival rates are the most commonly used outcome measures for patients with cancer. Recently, this new survival analysis method, called “period analysis, has been introduced to derive more ‘up-to-date’ estimates of long-term survival rates. Using cohort-based types of analysis, traditional long-term survival statistics essentially reflect the survival expectations of patients diagnosed many years ago. As a result, they are frequently severely outdated at the time they become available.

Patients were stratified according to gender and age at the time of diagnosis. The age groups were 15-44, 45-54, 55-64, 65-74, 75-84, and 85 years or older. The researchers used a statistical model known as a mixture cure model to determine the proportion of long-term survivors by gender and age category. Cancer-targeted therapies are associated with survival patterns that differ from older treatments, including survival curves that plateau after a certain follow-up time point. A fraction of the patient population is then considered statistically cured and subject to the same mortality experience as the cancer-free general population. Mixture cure models account for this characteristic.

For males, the five-year adjusted relative survival rate progressively improved from 72% (dx 1985-1989) to 88.2% (dx 2010-2014). Similarly, the ten-year adjusted relative survival rate advanced from 47.3% to 72.5% for men diagnosed in those two timeframes.

 

Females fared even better with a five-year adjusted relative survival rate of 76.8% (dx 1985-1989) to 90.8% among those diagnosed between 2010 and 2014. Ten-year adjusted survival among females rose from 58.2% to 78.7% for the two timeframes of their diagnosis.

This statistical analysis shows that survival has significantly improved by calendar periods among patients diagnosed after 2004 and treated in the era of advanced therapies.

While this data is encouraging, we should remember that the data used in this study is already four years old. Furthermore, many of the drugs now available were not commercially available throughout the study timeframe. Ibrutinib (Imbruvica®) and idelalisib (Zydelig®) gained FDA approval in 2014, venetoclax (Venclexta®) followed in 2016. Acalabrutinib (Calquence®) did not get approved until 2019. These drugs were in clinical trials during the entire second review period of 2010 to 2014, so they exerted some effect on survival data, albeit small given the size of most clinical trials

Therefore, we can assume that the growing use of targeted therapies can only show further advances.
Females and younger patients had a higher probability of long-term survival.
Like many studies, this study opens the way for follow-up, and other variables such as treatment type, disease stage, and genetics could be incorporated.

This study is an example of today’s pharmacists’ valuable role in the care and research of cancer patients. For more information on the role of the pharmacist in CLL care, click here.