Prostate cancer is often a multifocal disease, which means that multiple tumors can be present in different parts of the gland at the same time. However, not all of these tumors are equally problematic. And it is increasingly believed that the tumor with the most aggressive features – called the index lesion – determines how a man’s cancer is likely to behave overall. This concept has led to a new treatment option. Partial glandular ablation (PGA), also known as focal therapy, only treats the index lesion and surrounding tissue, rather than surgically removing the prostate or otherwise treating the entire gland. New evidence suggests that PGA is effective at fighting prostate cancer, but with fewer complications such as incontinence.
In February, researchers at the Memorial Sloan Kettering Cancer Center (MSKCC) in New York published results that could pave the way for focal therapy in men with recurrent prostate cancer. They specifically focused on men whose cancer had returned an average of three to four years after their first exposure.
Their preliminary results suggest that doctors can use MRI and biopsy results to select which patients with recurrent prostate cancer might be eligible for PGA. The research was carried out by Dr. Gregory Chesnut, an MSKCC urologist.
During their study, Chesnut and his colleagues first identified 77 men who were treated for recurrent prostate cancer at MSKCC between 2000 and 2014. All men had originally received radiation for their prostate cancer to cure the disease, but the cancer had come back. At that time, their prostate was surgically removed. Subsequently, parts of their tumors were mounted on slides for examination by a pathologist and then stored.
By looking at these slides with sophisticated instruments, Chesnut’s team was able to figure out where each tumor was located in each of the men’s prostates. The team also had access to preoperative information showing that 15 of the men were candidates for PGA by current criteria. To be considered for PGA, men must have a treatable index lesion and the absence of highly aggressive cancer cells outside of the immediate vicinity of the tumor. This is evident from biopsy and MRI findings.
What the results showed
What Chesnut and his colleagues wanted to know was whether the men’s preoperative findings matched the tumor details in their surgically removed prostate. And that turned out to be the case. The men had truly treatable index lesions with no other aggressive cancer, which meant the biopsy and MRI results had accurately predicted PGA eligibility. In addition, six other men were found to be eligible for PGA based on tumor slide analysis, although preoperative and MRI findings suggested otherwise.
With this in mind, the authors concluded that 21 of the original 77 men, or 27% total, had recurrent prostate cancer accessible to PGA.
While the results are promising, the authors also cautioned that given the small number of men evaluated and other limitations of the study, they are currently unable to recommend PGA as a treatment for recurrent prostate cancer outside of clinical trials.
“The authors addressed a very important problem to which there are no easy answers. This has to be done with recurrent or persistent prostate cancer after radiation therapy,” says Dr. Marc Garnick, Professor of Medicine at Gorman Brothers at Harvard Medical School and Beth Israel Deaconess Medical Center, Editor of Harvard Health Publishing Annual report on prostate diseasesand Editor-in-Chief of HarvardProstateKnowledge.org.
“Performing a radical prostatectomy to remove the prostate after radiation therapy is a complicated procedure that has potentially significant urinary side effects. Alternatives that can help eradicate persistent cancer in an irradiated gland and thereby reduce side effects are an important advance. These new findings should reassure men undergoing PGA that aggressive cancer in the prostate will not go untreated. The results are also important in that patients can be offered a second chance to remove residual or recurring cancer without the need to surgically remove an already radiation-treated prostate. Further studies should examine these results in a larger number of patients. “