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New blood test shows if Zytiga before docetaxel chemotherapy is working


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Jim Marshall (not a doctor) said ...

Zytiga (abiraterone) is a drug that can be used to treat prostate cancer when it has both:

  • spread to other parts of the body (metastatic); and
  • no longer responds to hormone treatment (castrate-resistant).

When both these things happen, it is called metastatic castrate-resistant prostate cancer (mCRPC).


Zytiga may be given either before or after the common chemotherapy drug Taxotere (docetaxel).


When studying the use of Zytiga before docetaxel:

  • PSA was not a good guide because it doesn't always initially go down, even if the Zytiga is working; and
  • metastases on scans often don't initially fade, but brighten, even if the Zytiga is working.


So doctors took regular blood tests to find something that would tell them when the Zytiga before docetaxel was working. 


The best measure they found was at 12 weeks after starting. 


The blood test combined:

  •  a count of the cancer cells in the blood shown by the Circulating Tumor Cells (CTC) test; and
  • levels of tissue damage shown by the Lactate Dehydrogenase (LDH) test.


Twelve weeks after starting treatment, men with low circulating tumor cells (4 or less) and normal LDL had a 46% chance of being alive 2 years later.


Twelve weeks after starting treatment, men with high circulating tumor cells (5 or more) and high LDL (greater than 250 IU/L) had a 2% chance of being alive 2 years later


Researcher Howard Sher recommended that men in this second group be moved on to different treatment.


Use of Zytiga after docetaxel is paid for by the Pharmaceutical Benefits Scheme (PBS) in Australia.

Use of Zytiga before docetaxel is not covered by the PBS at the time of writing (Oct 2013), and costs more than $3000 per month.

... end Jim

See a fuller report at:

Biomarkers Predict Prognosis for Patients With mCRPC 

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