comment on Leap of Faith to Discover Cancer Signatures

[Guest guest]

Add Patience to a Leap of Faith to Discover Cancer Signatures

http://nyti.ms/mZv4bJ

snip " The hunt for cancer signatures also is a type of work that requires a

leap of faith. It is impossible for scientists to use their intuition to

know whether a signature has any biological meaning - it is just a pattern,

and the meaning comes from its statistical association with a result. "

I've copied this part of the article because I've received questions about

the utility of gene-expression profiling in lymphoma and I think the above

statement explains why such a test is meaningless outside of a trial.

For lymphoma, the present emphasis seems to be on making use of cytogenetic

markers from paraffin-fixed tissue blocks (because that tissue is already

available) -- to correlate outcomes (response etc) with markers (features of

the sample) suspected of being linked to treatment resistance. (Correlative

Companion studies)

So, for this area of clinical research to move forward, there's a need for

biopsy tissue and other samples taken and stored in a standard way,

annotated, coded - (de-identified to protect privacy), and linked to

clinical results (to do the correlations).

Without all of the above in place and without the correlations validated

(replicated) prospectively ... it remains investigational -- Not ready for

clinical decision-making - but potentially vital as the basis for companion

studies for interventional studies.

Notably, progress has already been made in CLL along these lines, with

compelling associations between cytogenetic markers and response to specific

chemo agents. So how close we are to making progress can depend on the

specific type of lymphoma - and CLL is a type of lymphoma.

Regarding genetic " signatures " of tumors it has been described as an

avalanche of data. One hope is that a particular marker (one or a few

mutations or genes over-expressed) may be used as a surrogate for the

complex signature - enabling a cheaper and simpler test to help guide

clinical practice - to tailor therapy to the individual in future.

None of the above is possible without having a sufficient number of patients

willing to participate in trials. Just my two cents : )

__________________

All the best, ~ Karl

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