THE "NEW" PROSTATE CANCER INFOLINK

By now, many readers have probably seen news reports coming out of Australia about the “possible medical breakthrough” of a rapid, highly accurate test that can be used to detect cancer anywhere in the body (prostate cancer specifically included).

We had noted the earliest reports about this test yesterday but hadn’t reported on this ourselves because we were waiting to get some more independent feedback on what others in the cancer research community thought about the claims being made.

The paper by Ibn Sina et al. was published on Tuesday in Nature Communications. The full text is available on line for those who want to try to make sense of it. Publication of the paper was accompanied by this statement from the Australian Institute for Bioengineering and Nanotechnology at the University of Queensland on Wednesday. The media flood started late yesterday.

Your sitemaster thinks it is important that we make a number of things very clear up front:

• There is quite definitely a technological breakthrough here. The ability to use a new type of DNA methylation to identify risk for cancer represents a whole new way to think about the clinical diagnosis of cancer. However, to quote the authors themselves:
• “We certainly don’t know yet whether it’s the Holy Grail or not for all cancer diagnostics, but it looks really interesting as an incredibly simple universal marker of cancer, and as a very accessible and inexpensive technology that does not require complicated lab based equipment like DNA sequencing.”
• In it’s current form, this test “is only able to determine the presence of disease and a detailed analysis is required to fully understand the type, stage and disease recurrence.”

To date, from a clinical perspective, the research team has reported using the new “Methylscape” test on just 72 epigenomic specimens from patient’s tumor tissues of differing types:

• 54 ER-positive breast cancer tumors
• 8 prostate cancer tumors
• 10 lymphoma tumors

They compared the ability of the test to identify cancer in these tissues with 31 matching epigenomic specimens from healthy patients:

• 19 with normal breast tissue
• 10 with normal prostate tissue
• 2 with normal lymph node tissue

This will clearly show the informed reader that we have a long way to go before this new test can be used to actually diagnose specific types of cancer in specific types of cancer patient.

Issues that are going to need to be resolved before we can really tell how valuable the Methylscape test might be in the diagnosis of cancer include the following:

• Is the biomarker really common to all forms of cancer or only certain subforms?
• What other, supplementary tests might be necessary to determine whether the forms of cancer identifiable by this test are actually clinically significant?
• Could it be used as an accurate screening test for risk of a variety of types of cancer?

The greatest danger of a test like this is that it might be so good that it can identify the very earliest forms of cancer which, in the majority of people, are normally killed off quickly by the immune system. In other words, it might be able to detect clinically insignificant cancers with the same degree of accuracy as clinically significant cancers (which, in the case of prostate cancer, is what the PSA test can do, to some extent). Such a test could then raise the specter of risk for unnecessary treatment of clinically insignificant cancers to an even higher level.

The “New” Prostate Cancer Infolink wants to be extremely clear to our readers that this new technology is fascinating and holds huge potential — both as a research tool and perhaps as a clinical tool too. It seems to be simple and quick to apply. However, at present …

• It has only been tested on DNA in actual tumor tissues.
• We don’t know if it could be used to find cancer in a blood specimen or a urine specimen or similar (which means there are questions about its potential as a screening test for cancer).
• We don’t know enough about the consistency and repeatability of the findings.

Consequently, it will probably be some considerable time before we know what the real value of this test is in the detection and management of cancer in the “real world” as opposed to the laboratory.

Filed under: Diagnosis, Management, Risk | Tagged: cancer, DNA, methylation, Methylscape, test |