Treating High-Risk Bladder Cancer and Analyzing PSA Screening for Prostate Cancer: Research From the 2021 Genitourinary Cancers Symposium

Genitourinary Cancers Symposium
February 8, 2021
Brielle Gregory Collins, ASCO staff

The 2021 Genitourinary Cancers Symposium will be held virtually February 11 to 13. This conference highlights research on improving the treatment and care of people with genitourinary cancers, including those with bladder cancer, kidney cancer, penile cancer, prostate cancer, and testicular cancer

You can learn more about research from this symposium by following the #GU21 hashtag on Twitter.

Summaries of 2 studies that will be presented at the symposium are described below:

  • Nivolumab after surgery in people with high-risk bladder cancer nearly doubles disease-free survival

  • Diagnoses of metastatic prostate cancer increased after rates of PSA screening were lowered

Nivolumab after surgery in people with high-risk bladder cancer nearly doubles disease-free survival

A phase III clinical trial called CheckMate 274 found that adding the immunotherapy nivolumab (Opdivo) for the treatment of muscle-invasive urothelial carcinoma with a high risk of recurrence nearly doubled disease-free survival. Disease-free survival is the length of time after a person receives treatment that no cancer is found.

Urothelial carcinoma is the most common type of bladder cancer. Muscle-invasive urothelial carcinoma is cancer that has grown into the muscle surrounding the bladder. The standard of care for people with muscle-invasive urothelial carcinoma is to give chemotherapy with cisplatin (available as a generic drug) before surgery to remove the bladder, called a radical cystectomy. However, some people with muscle-invasive urothelial carcinoma are unable to receive chemotherapy for various reasons. Chemotherapy given before surgery is called neoadjuvant chemotherapy.

Nivolumab is a type of immunotherapy called an immune checkpoint inhibitor that works by blocking the protein PD-1, which contributes to cancer cell growth and survival. By blocking PD-1, the immunotherapy helps the immune system to recognize and attack cancer cells.

This study included people with high-risk muscle-invasive urothelial carcinoma who were randomly assigned to receive either nivolumab (353 patients) or a placebo (356 patients) after surgery with or without neoadjuvant chemotherapy. The study found that those who received nivolumab had a disease-free survival of 21 months, compared with nearly 11 months in those who received the placebo after initial treatment. Among those whose tumors expressed PD-L1, a protein that interacts with PD-1, disease-free survival was also improved.

Patients receiving nivolumab more commonly experienced severe side effects (17.9%), compared with those who received the placebo (7.2%).

What does this mean? For people with high-risk muscle-invasive urothelial carcinoma, including those who cannot receive chemotherapy, nivolumab given after surgery may significantly reduce the chances of cancer coming back.

“Nivolumab is the first immune therapy to be used in the adjuvant setting that provides a statistically significant and clinically meaningful improvement in disease-free survival for patients with high-risk muscle-invasive urothelial carcinoma after radical surgery with curative intent, irrespective of PD-L1 status.” 

—   Dean F. Bajorin, MD, FACP, FASCO
Memorial Sloan Kettering Cancer Center
New York, New York

Diagnoses of metastatic prostate cancer increased after rates of PSA screening were lowered

Researchers have found that an increase in diagnoses of metastatic prostate cancer in the United States between 2008 and 2016 may be the result of less use of prostate-specific antigen (PSA) screening.

PSA is a substance found in the blood that is primarily made by the prostate gland. It can be found in higher levels in people with various prostate conditions, including prostate cancer. Using PSA testing to screen people for prostate cancer when they have no symptoms has been controversial. PSA testing is helpful in finding prostate cancer earlier and before it can spread to other parts of the body, but it can also lead to unnecessary or excessive treatment, which can have a significant impact on a person’s quality of life. In its guidance in 2008 and 2012, the U.S. Preventive Services Task Force (USPSTF) did not recommend PSA screening for most individuals. In 2018, the USPSTF issued new recommendations that individuals aged 55 to 69 should discuss with their doctor whether PSA screening is right for them.

In this study, researchers gathered data on the number of diagnoses of metastatic prostate cancer from 2002 to 2016 using the North American Association of Central Cancer Registries. They collected PSA screening estimates from each state from 2002 forward using the Behavioral Risk Factor Surveillance System, which gathers this data every 2 years for people at least 40 years old. From there, researchers used a statistical model to see if there was a relationship between rates of PSA screening and the number of diagnoses of metastatic prostate cancer.

The researchers found that from 2008 to 2016, the average percentage of people screened for prostate cancer decreased from 61.8% in 2008 to 50.5% in 2016. Meanwhile, the average incidence of metastatic prostate cancer at diagnosis increased from 6.4 cases per 100,000 men to 9 cases per 100,000 men. The rates of screening and prostate cancer varied greatly between states. Statistical analysis indicated that states with a bigger decrease in PSA screening had larger increases in metastatic prostate cancer diagnoses. Further statistical analysis indicated that variations in PSA screening contributed to the differences in the rates of metastatic prostate cancer.

What does this mean? In states where less PSA screening was used, researchers found an associated increase in diagnoses of metastatic prostate cancer. This underscores why it is important for patients and doctors to discuss whether PSA screening is right for them.

“The variation between states is one of the precise strengths of our study. The magnitude of decreased PSA screening was correlated to the magnitude of increased metastatic disease, suggesting that there may be a link at population level.”

—   Vidit Sharma, MD
University of California, Los Angeles
Los Angeles, California

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