When a hive of honeybees becomes overpopulated, about half the bees leave the hive in a swarm to colonize a new site. There could be hundreds of bees in the swarm, and once the swarm is gathered in an intermediate place, a subgroup of scouts break away to explore and find several potential new sites which they communicate to each other by a sort of dance that shows a map to each location. When they reach a quorum (majority agreement) on the right choice, they return to the swarm and “dance” the map so all the bees know which way to travel. Amazingly, the whole swarm departs at once and arrives safely at the new hive—and this usually occurs in only three days! Imagine hundreds of humans arriving at agreement and following agreed-upon directions in only three days!
The French impressionist painter Edgar Degas may not be as famous as Monet or Renoir, but he came up with a memorable observation about dialogue among experts: “What a delightful thing is the conversation of specialists! One understands absolutely nothing and it’s charming.” There is, however, a great way for experts to do something similar to the bees, and arrive at very understandable principles for others to follow in order to achieve a common goal. It’s called the Delphi consensus method. It’s a series of stages or rounds involving repeat questionnaires. Each stage progressively filters out minority disagreements to finally arrive at the greatest agreement, or consensus.[i]
Recently a group of 47 internationally recognized prostate cancer experts – including urologists and radiologists – embarked on a Delphi project to determine how to select prostate cancer patients for focal therapy.[ii] This is a topic that has sparked many questions, such as
- Is “insignificant” prostate cancer amenable to active surveillance and/or focal therapy?
- Is focal therapy for Gleason 3 + 4 disease? What about Gleason 4 + 3?
- How can one be sure there isn’t microscopic disease elsewhere (multifocal)?
- How should patients be monitored after focal therapy? Etc.
There are important reasons to arrive at consensus. The most important, of course, is the safety and quality of life for patients. Another key factor is uniformity of choosing patients, in order to arrive at meaningful analysis when data is collected and compared from a multitude of treatment sites and clinical studies. To continue with the honeybee example, think of the “swarm” of physicians who already believe that focal therapy is a valid way to control prostate cancer while minimizing the risk of side effects associated with whole gland treatments (prostatectomy and radiation). They all seek a new “home base” of confidence that they are properly choosing patient candidates, because it is irresponsible to undertreat any cancer, including prostate cancer.
Thus, we might think of the 47 Delphi participants as the “scouts” who must arrive at a quorum in order to direct their hundreds – or even thousands – of colleagues who want to settle in to a set of guiding principles for patient selection.
The “scouts” did a marvelous job of identifying those principles. To set a standard, they defined consensus as agreement among at least 80% of participating physicians. Finally, a subgroup of 16 participants met in person “to review the data and formulate the consensus statement.”[iii] Among their areas of consensus, they stipulated the following principles for selecting patients:
- Multiparametric MRI (mpMRI) is a standard imaging tool for evaluating and choosing patients.
- If mpMRI detects a suspicious lesion, a biopsy into that lesion is necessary for diagnosis.
- Areas on imaging that don’t reveal anything suspicious should be interrogated by systematic biopsy to validate they are negative for cancer. (However, adequate criteria for systematic biopsy has not yet been determined.)
- Focal therapy can be recommended for low-to-intermediate risk cancer “including Gleason 4 + 3 disease.
- Gleason 3 + 4 disease, “where localized, discrete and of favorable size represents the ideal case” for focal therapy.
- Tumor size must be considered, and the project spelled out limits.
Among other agreed-upon considerations were: the extent of any insignificant disease that is safe to leave untreated, subject to surveillance; and pre-existing ED did not exclude an otherwise qualified patient from focal treatment.
The Sperling Prostate Center is the leading source for Focal Laser Ablation (FLA). We are seeing more and more patients who have actively sought out FLA. We know that they, and thousands of patients like them, are confronted by naysayers and skeptics. We recognize that it often takes courage and tenacity to follow one’s desire for focal treatment. The Delphi committee took much longer than three days to arrive at the map that leads to a new home base of confidence. We hope this map will guide those who are drawn to the idea of focal therapy but are still unsure of how to get there. Perhaps now the “swarm” of focal therapy practitioners will grow, patients will find much more support, and insurance companies will begin reimbursing focal treatments. We extend a big thank-you to all who participated in the Delphi Consensus Project.
[ii] Tay K, Scheltema M, Ahmed H, Barret E et al. Patient selection for prostate focal therapy in the era of active surveillance: an International Delphi Consensus Project. Prostate Cancer Prostatic Dis. 2017 Mar 28. doi: 10.1038/pcan.2017.8. [Epub ahead of print]