Updated Nomogram Predicts Modern Outcomes After Salvage Radiotherapy Following Radical Prostatectomy

Rahul Tendulkar, MD

A contemporary update of a 2007 predictive nomogram for salvage radiotherapy after radical prostatectomy offers a modernized forecast of cure compared to its predecessor.

“This (updated nomogram) can have an immediate impact by providing patients and clinicians with an accurate and personalized method of predicting their chances of successful treatment,” says Rahul D. Tendulkar, MD, of Cleveland Clinic Cancer Center, lead author on the study that informs the nomogram update. “It may also help patients and clinicians decide whether to be more aggressive with treatment, or perhaps consider participating in a clinical trial. Also, it may help determine the urgency of treating patients sooner rather than later.”

Original nomogram was first of its kind

A nomogram incorporates multiple data points and returns a graphical computation, simplifying decision-making. The 2007 nomogram was the first of its kind for predicting the outcome of salvage radiation therapy (SRT) for recurrent prostate cancer after prostatectomy. It was created by Andrew J. Stephenson, MD, who is currently the Director of the Center for Urologic Oncology at Cleveland Clinic. It demonstrated that an increasing serum prostate-specific antigen (PSA) level was the initial sign of recurrent prostate cancer among patients treated with radical prostatectomy (RP).

SRT might eradicate locally recurrent cancer, but studies to distinguish local from systemic recurrence lacked sensitivity and specificity, Dr. Stephenson noted in 2007. The original nomogram predicted the probability of cancer control at six years after SRT for PSA-defined recurrence by evaluating markers such as cancer stage, tumor grade and PSA level.

Updated nomogram focuses on treatment at earlier signs of recurrence

The updated 2016 nomogram takes into account the more recent trend of treating patients at lower PSA levels than in the past (“early SRT”). Randomized trials published since the original nomogram was created have demonstrated the benefit of early SRT in high-risk patients.

“We found that treatment at lower PSA levels does indeed improve the chance of cure,” says Dr. Tendulkar. He describes the updated nomogram in an abstract presented to the 57th annual meeting of the American Society for Radiology Oncology (ASTRO) in San Antonio, Texas.

The 2016 study was a multi-institutional collaborative effort including more than 2,400 patients from 10 institutions. It represents the largest series in the literature regarding SRT after RP, Dr. Tendulkar says.

The retrospective cohort study examined 2,460 patients with a median follow-up of 5 years from the end of radiation. Early SRT was associated with improved freedom from biochemical failure and freedom from distant metastases.

The updated nomogram is designed to better estimate individual patient outcomes after SRT. “The nomogram can give an estimate of the five- and 10-year rates of developing (or not developing) a biochemical recurrence (by elevated PSA) or distant metastases,” says Dr. Tendulkar. “While we describe rates at specific benchmark times, in some cases late recurrences can indeed happen.”

New nomogram will be available to clinicians, patients worldwide

Once the study is published, the nomogram will be made available online at no charge. “Patients and clinicians worldwide can utilize the information to help make decisions regarding treatment,” says Dr. Tendulkar.

Were findings a surprise? “Our hypothesis was consistent with the study outcome,” he says. “We have known that certain factors can predict patient outcomes. This nomogram provides a more refined predictive tool than previously available.”

The next steps, says Dr. Tendulkar, will include conducting subset analyses to learn more about which patients need what kind of treatment. Ideally, clinical trials could be designed based on these findings.