Additional data supportive of clinical value of Prolaris test


A new report in the British Journal of Cancer suggests that data provided through Myriad Genetics’ Prolaris™ test may be “the strongest independent predictor of cancer death outcome yet described” for the management of men with clinically localized prostate cancer.

As our regular readers will be well aware, there is enormous variation in the natural history of prostate cancer among individual patients. The Prolaris test is designed to measures the level of expression level of some 31 genes involved with cell cycle progression (CCP) and then to use to the CCP score to predict disease outcomes over time.

Cuzick et al. have now correlated clinical data (centrally re-reviewed Gleason scores, baseline PSA levels, ages, clinical stages,and extent of disease) with CCP scores for 349 men initally diagnosed with prostate cancer by needle biopsy and managed conservatively over time (i.e., with either active surveillance or watchful waiting). Long-term follow-up data were also available for these 349 patients.

The results of their study show that:

  • Based on univariate analysis
    • The hazard ratio (HR) for death from prostate cancer was 2.02 for a one-unit increase in CCP score, and this was highly statistically significant.
    • The CCP score was only weakly correlated with standard prognostic factors.
  • Based on multivariate analysis
    • The HR for death from prostate cancer was 1.65 for a one-unit increase in CCP score, and this was still highly statistically significant.
    • The patients’ initial Gleason scores and PSA levels provided significant additional contributions.
  • The 81 percent of patients with lower CCP scores when left untreated had a 5-year survival rate of 93 percent.
  • The 19 percent of men with higher CCP scores when left untreated had a 5-year survival rate of 63 percent and a 10-year survival rate of 44 percent.

In a media release from Myriad Genetics, Jerry Lanchbury, PhD, the chief scientific officer of the company and a co-author of this paper stated that, “We believe this test will provide critical information needed to avoid unnecessary and life altering morbidities associated with treating the disease in men who have a less aggressive form of prostate cancer.”

Once again, we need to note that these data, which are certainly supportive of the potential of the Prolaris test, are based on retrospective rather than prospective study of the value of the test. To be absolutely compelling, we still need to see data from prospective studies of the use of this test, i.e., studies in which the tests is used at the time of diagnosis to project patients’ outcomes over time, with biochemical progression-free, metastasis-free, prostate cancer-specific, and overall survival as the study outcomes.

The cost of the Prolaris test is of the order of $3,400. This may not be excessive for a one-time test if it really can predict with high accuracy the probability of death from prostate cancer in specific individuals, since the costs of many of the tests and of first-line treatment may be saved. However, we have a ways to go before we can say with certainty that the Prolaris test can acuurately differentiate, in a prospective manner, between those men needing first-line treatment and those who can be managed conservatively.

4 Responses

  1. Guys, I appreciate your conservative approach, but I think it’s time to start letting men know about the availability of this test, uncertainty and all. I had a prostate cancer scare about 6 years ago, and if this test had been available, I would have gladly paid for it out of my own pocket.

    Life is uncertain, and there is no way to make absolutely sure we won’t die of prostate cancer. Men facing the specter of a prostate cancer diagnosis should have the very best information (caveats and all) to make the best possible decision for their own life. This latest study puts the test well into the “much better than what we currently have” category. Will we let the perfect be the enemy of the good? In reading one of the previous articles on the topic, the author commented that we really need a test based on a blood or urine sample. Is that really a valid reason to downplay the importance of this test? What we really need is a vaccine that will immunize us against any form of prostate cancer. I’m not going to let that stop me from using the treatments we do have. The Obamacare death panel (preventative medicine task force) has a draft recommendation sitting out there suggesting all routine PSA screening be halted. That seems a bit extreme. Seems to me that this test combined with PSA screening makes the most sense right now. This test may also help to put the brakes on doctors almost automatically recommending a radical prostatectomy. The introduction of the “robot” into the market may be improving outcomes some, but it is also doing two other things: (1) increasing the profit motive to recoup the investment in training and equipment; (2) giving both the patient and the doctor a false sense of the likelihood of a side effect-free operation. My thoughts are with the 4,000 guys who will get positive biopsy results this week — they should know about this test.

  2. With Gleason 9 prostate cancer, and having undergone RRP, adjuvant RT, plus AHT, I now face a recommendation to undergo adjuvant chemotherapy. I’m hoping this test and possibly others can be used to help me make up my mind whether to proceed. I am not eager to start chemotherapy with a PSA of < 0.01 (despite a miniscule rising post-operative PSA before RT and AHT).

    Even my oncologist gives me only a 10% chance of the adjuvant chemotherapy having any curative effect. From my research, docetaxel has been shown not to be curative when applied in a neoadjuvant setting, and one study indicated that it in fact creates pathways in the prostate cancer that have been associated with metastasis.

    So, a test like this (or the upcoming SPARC test) offers a way to possibly rule out an expensive and potentially harmful treatment option.

  3. I am not aware of any data (yet) that would validate the use of the Prolaris test in the manner you describe in men with your clinical profile. On the other hand, I do completely appreciate your viewpoint on the value of docetaxel in your circumstances.

  4. I have reviewed this information and have not seen additional value beyond free nomograms. There is no prognostic ability, only predictive ability which means there is no threshold for physicians to make treatment decisions with the information, as it is only as good (if not perhaps slightly better) than using the Kattan nomogram or the Capra S score. For $3,400, it is not worth the price for me.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 1,074 other followers