Ideal investigation after prostate biopsy confirmed Ca is . Bone scan or Pet Ct

• 14 Feb 2020 05:47:48 PM
• |General Urology

As a urologist we do psa and biopsy . After confirmation of ca to r/o mets a bone scan is advised but i find that when these pts visit a oncologist at this stage they advise  a PET CT. I want the opinion of the house is it a bone scan or pet ct as there id a huge cost to it

Comments(3)

• 

  Nitesh Jain

  15 Feb 2020 06:23:19 AM

  If we go with the guideline the ideal investigation is a Abdominopelvic imaging in form of MRI (preferred) or CT with a bone scan ...

  
  

  Only PSMA PET scan doesnot give good anatomical details so unless combined with MRI fusion is not a great tool if contemplating any local treatment specially surgery 

  
  

  PSMA PET OR PET SCAN :

  
  

  Not recommended 

  Because :

  1. Expensive

  2. Not widey available 

  3. User and Machine dependent 

  4. It’s just a functional study, doesnot tell about local staging unless combined with MRI fusion which again is not widely available 

  5. Detects mets earlier than most conventional mets , bone mets pick is 30% higher than the conventional imaging (bone scan) based on which most of the major trials are based so stage migration is higher “Will Rogers Effect” so more patient is getting treated by expensive drugs which may be unnecessary 

  6. Not yet approved by FDA for routine staging for Ca P

  
  

  Advantage :

  
  

  1. Good for recurrence 

  2. Small soft tissue mets can be better identified 

  3. Picks up LN well

  4. Good for biochemical recurrence where other imaging is negative

• 

  Amrith Raj Rao

  15 Feb 2020 11:21:21 PM

  Dear All,

  
  

  As with many other investigations, its only time, when everyone will adopt PSMA-PET CT Scan (or MRI). 

  
  

  Few valid points raised by Nitesh. Will respond point by point 

  
  

  Because :

  1. Expensive

  A. Yes - at the moment it is expensive but you are getting an accurate staging for CaP. For eg - if there are mets seen, then you wouldnt go down the route of Radical Treatment with intent to cure. 

  Again, if you are not going to do PET CT, then you have to carry out MRI abd and pelvis + Bone Scan (therefore, cost of both). 

  Now if one is talking abt MRI post-biopsy - it is fraught with post-Bx artefacts, therefore, "accurate" local staging is not always possible. Therefore, most Western countries and many centres in India, you carry out MRI scan prior to Bx. 

  
  

  2. Not widey available 

  A. PET is now available in most capitals and in multiple hospitals. Urologists are lagging behind other specialties with regards to PET imaging. PET is mandatory in many other malignancies and the patients travel to have it done if it is mandatory. 

  
  

  3. User and Machine dependent 

  A. Agree. But it is easier to interpret PET CT than MRI! 

  
  

  4. It’s just a functional study, doesnot tell about local staging unless combined with MRI fusion which again is not widely available 

  A. Agree. And I go back to Q1 regarding pre-Bx MRI. Certain centres are utilizing PET MR fusion but again post-Bx. 

  
  

  5. Detects mets earlier than most conventional mets , bone mets pick is 30% higher than the conventional imaging (bone scan) based on which most of the major trials are based so stage migration is higher “Will Rogers Effect” so more patient is getting treated by expensive drugs which may be unnecessary 

  A. I have debated this in the past regarding Will ROgers phenomenon. Herein, you are avoiding a major intervention if you detect Bone Mets. THerefore, the argument abt WRP does not arise. Having said that, one has to be cautious about PSMA PET CT scan as well. There are false negatives as well. 

  
  

  
  

  6. Not yet approved by FDA for routine staging for Ca P

  A. FDA takes a long time in such circumstances. There are some trials going on in Audtralia which will probably help in getting FDA nod. 

  
  

  For me, even more exciting abt PSMA is the utility in Theronostics. Luetium PSMA directed therapy for mets. It sounds very promising. 

  
  

• 

  Venugopal P

  17 Feb 2020 06:28:14 PM

  Dear All,

  Most of the queries raised by Nitesh have been answered by Amrith point wise. As mentioned by Amrith, most new evaluations will initially be expensive and the same was with mpMRI as well. We now know that even with mpMRI, number of P Ca’s could be missed. No one evaluation can be 100% accurate. I am providing two articles that some of the issues concerning PSMA PET/CT. The issue being discussed is concerning its ability to pick up primary prostate cancer in the lobes of prostate and the answer, though not yet completely validated appear as YES.

  http://jnm.snmjournals.org/content/57/11/1720.full.pdf

  https://cancerimagingjournal.biomedcentral.com/track/pdf/10.1186/s40644-018-0175-3

  As regards detecting Metastases are concerned, PSMA PET/CT has much better benefit than most investigations now available. As Kalloor of HCG Bangalore mentions that ‘PSMA PET/CT or MRI Fusion is a one stop test as regards P Ca’. This is shaping to be true.

  As mentioned by Amrith, PSMA with its various ligands will be the way to move forward. It is very likely in a few years to come mpMRI will take a back seat in the diagnosis of P Ca as diagnosis of Primary and its aggressiveness can be detected by these evaluations and staging of P Ca can be made with considerably more accuracy. I do not know whether we will say in a short time ‘may mpMRI rest in peace’.

  With warm regards,

  Venu