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Thread: Does PET scan give more details than CT scan?

  1. #1
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    Does PET scan give more details than CT scan?

    Hi,

    I was diagnosed 18 months ago with tumor in the tail and metastasis the liver. 9 cycles of folfirinox followed by surgery to remove the primary tumor, but I still have mets to the liver. During the chemo mets reduced significantly in size, the larges when from 5 cm to 1.3 cm. I have not done chemo for 12 months and the mets have been stabile. I am checked every 3 months with CT, and have not done a PET scan since I got diagnosed. I have done a couple of MR scans to evaluate the liver to se if I was a candidate for liver directed therapy, bu so fare no PET scan. So I am wandering if a PET scan could give a better and more detailed picture of the metastasis in my liver, and whether they are active or not. My oncologist is surprised that the mets has not started growing, one theory he had was that my immune system currently are able to kill new cancer cells and therefor no increase in size. Will a PET scan be able to identify smaller metastases than the CT scan are able to? Next scan is in August, so I am considering to ask my oncologist for a PET scan.
    December 16 - diagnosed with Acinar Cell Carcinoma w/ metastasis (7) to the liver
    January 17 - started treatment w/FOLFIRINOX
    February 17 - allergic to Neulasta, had to stop taking the shots
    March 17 - 50% reduction of tumor and metastasis after 4 treatments
    May 17 - CT scan after 8 treatments: tumor 17x22 mm and well defined
    May 17 - Stoped FOLFIRINOX after 9 cycles to prepare for surgery
    June 17 - Surgery 22 June, Distal pancreatectomy, removed tail/body, spleen and 6 lymph nodes (all negative)
    Genetic profiling done via PanCan: No BRCA mutations, but SMAD4, CTNNB1 and MLL2
    May 17 - November 18 CT show stabile disease - no new or enlarged mets

  2. #2
    Super Moderator Top User ddessert's Avatar
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    The PET scan will show what areas are still active. I think it's best when done with the CT scan so that the tumor sites can be aligned with the PET scan activity.

    There may be tumor sites that show on a CT scan but do not show up in the PET scan and that might indicate a tumor that is not active and probably not affected by chemotherapy. It's also possible that those are scar tissue sites and that there is no tumor there (scar tissue looks like just a tumor on a CT scan).

    My oncologist would say that if the tumor does not light up on the PET scan, then there's little value in using chemotherapy on it.
    Last edited by ddessert; 06-12-2018 at 03:26 AM. Reason: CT -> PET in last sentence
    BRCA2 3398del5
    Dec 2010 - back/abd pain
    May 2011 - Unresectable stage III, 2.5cm tumor
    Jun-Aug 2011 - Gem/Cis, 9 rounds
    Oct-Nov 2011 - Radiation+Xeloda, 25 days in 5 weeks
    Oct 2011-Sep 2012 - shrinking tumor
    Feb 2012 - National Familial Pancreatic Study
    Aug 2012 - Downgraded to stage IIA, PGP
    Sep 2012 - Whipple, T3N0M0, 0.5cm tumor, 0/16 lymph nodes
    Dec 2012 - Quebec PanCan Study
    Sep 2012-May 2018 - NED
    Mar 2013-present - NCT01088789
    @pancanology

  3. #3
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    Quote Originally Posted by ddessert View Post

    My oncologist would say that if the tumor does not light up on the CT scan, then there's little value in using chemotherapy on it.
    Hi David, did you mean PET scan in the last paragraph?
    Oct 2017 - Mom's annual checkup found elevated CA19-9 (280 kU/L)
    Nov 2017 - Diagnosed. Pancreatic Adenocarcinoma on body/tail of pancreas, ~3cm mass
    Dec 2017 - Distal pancreatectomy, 3.5*3*2 mass removed, 2/17 lymph nodes.
    Jan 2018 - CA19-9 dropped to 30 kU/L 4 weeks after surgery.
    Feb 2018 - 3 rounds of S1
    June 2018 - CA 19-9 from 50 to 170 KU/L. CT + PET confirmed recurrence at remainder of pancreas + peritoneal mets.
    July 2018 - Started Gem/Abraxane
    Sep 2018 - Peritoneal mets disappeared on CT. CA 19-9 dropped to 35.
    Nov 2018 - Finished 4th round of Gem/Abraxane. Clear CT. CA19-9 dropped to 22.

  4. #4
    Super Moderator Top User ddessert's Avatar
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    Yes, thanks for the catch. I will edit the posting in case others do not read your correction.

  5. #5
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    Thanks David, your comments makes sense to me. I am therefor a bit surprised that I have not done any PET scan yet. Since I have done 12 months without chemo now, and the spots on the liver stay the same size it would be interesting to know if it is scar tissue or active cancer that my immune system keep under control. As of now I am classified as incurable, but my ultimate goal is to be reclassified to a patient they at least will try to cure. Thecncally they can operate on my liver, but so fare they have argued that the risk for recurrence is to high. But after a year with out chemo and no sign of the cancer growing it might be time to do a new assessment.
    December 16 - diagnosed with Acinar Cell Carcinoma w/ metastasis (7) to the liver
    January 17 - started treatment w/FOLFIRINOX
    February 17 - allergic to Neulasta, had to stop taking the shots
    March 17 - 50% reduction of tumor and metastasis after 4 treatments
    May 17 - CT scan after 8 treatments: tumor 17x22 mm and well defined
    May 17 - Stoped FOLFIRINOX after 9 cycles to prepare for surgery
    June 17 - Surgery 22 June, Distal pancreatectomy, removed tail/body, spleen and 6 lymph nodes (all negative)
    Genetic profiling done via PanCan: No BRCA mutations, but SMAD4, CTNNB1 and MLL2
    May 17 - November 18 CT show stabile disease - no new or enlarged mets

  6. #6
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    Dessmo
    One of the reasons a PET scan is not done is the cost as compared to a CT scan. The medical team has to justify it versus a CT scan and my guess is that since everything is good and there appears to be nothing happening with you your team feels it would be hard to justify it to the insurance company. I am getting the results of my first PET scan later today to determine if I get more radiation treatment. Scanxiety is killing me!
    eds
    1/8/17 Diagnosed with Operable PanCan
    1/31/17 Started Immune therapy clinical Trial at Hopkins
    2/13/17 Whipple Surgery
    5/8/17 Completed SBRT treatment at Hopkins
    5/16/17 Started first cycle of Chemo Gemcitabine and Xeloda
    6/1/17 Admitted back into Hopkins with Gas in Abdomen from perforated bowel
    7/5/17 After a week in the hospital and a months rest delay Chemo for 3 months
    7/21/17 Quarterly CT Scan shows no evidence of Recurrence
    9/29/17 Quarterly CT Scan shows local recurrence of growth on the pancreas body
    10/11/17 Begin Folfirinox regimen for the foreseeable future
    12/27/17 After 4 cycles of Folfirinox Quarterly CT shows no spread of cancer and marginal shrinkage of tumor
    3/19/18 After 5 more cycles of Folfirinox my Quarterly CT Scan showed no spread.
    4/11/18 CA19-9 down from 4800 in December to 384
    6/8/18 PET Scan shows no mets, still local to pancreas. CA19-9 down to 165
    7/5/18 Started Proton Therapy at the University of MD, 36 treatments over 18 days

  7. #7
    Dessmo's in Europe. I doubt they have the same issues with insurance companies there. It's definitely not an issue in Japan. The doctor does what the doctor (or patient, often) deems necessary.
    February 2016- diagnosed with PC
    March 2016- inoperable due to arteries, also liver mets suspected
    March 2016-January 2017 -Gemzar/Abraxane
    February 2017 surgery-PC tumour and liver mets removed at same time
    July 2018 Back on Gemzar/Abraxane due to rising CA 19-9. Scans were clear.

  8. #8
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    Jackie is right, here in Norway we have a public healthcare system so money should not be the issue. I will ask my oncologist an see what he thinks. Thanks for the inputs, happy summer to you all!
    December 16 - diagnosed with Acinar Cell Carcinoma w/ metastasis (7) to the liver
    January 17 - started treatment w/FOLFIRINOX
    February 17 - allergic to Neulasta, had to stop taking the shots
    March 17 - 50% reduction of tumor and metastasis after 4 treatments
    May 17 - CT scan after 8 treatments: tumor 17x22 mm and well defined
    May 17 - Stoped FOLFIRINOX after 9 cycles to prepare for surgery
    June 17 - Surgery 22 June, Distal pancreatectomy, removed tail/body, spleen and 6 lymph nodes (all negative)
    Genetic profiling done via PanCan: No BRCA mutations, but SMAD4, CTNNB1 and MLL2
    May 17 - November 18 CT show stabile disease - no new or enlarged mets

  9. #9
    Moderator Senior User BrigitteM's Avatar
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    Sep 2016
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    Another possible explanation:

    I asked recently the question to my oncologist who said that CT scan was better for pancreatic cancers and PET scan less useful, implying that PET scans are better for certain other cancers. PET scan will show cancer activity, but I am not certain that it can determine accurate size of tumors or mets, unless it is doubled with a CT scan.
    __________________________________________________ ___________________
    1/12/2016 No symptoms except ongoing fatigue; blood test revealed elevated liver enzymes
    1/18/2016 Liver ultrasound, then MRI confirmed enlarged bile duct
    1/21/2016 ERCP and placement of a temporary stent
    1/28/2016 CT-Scan showed a lesion on the head of pancreas
    2/09/2016 2nd ERCP + EUS + FNA
    2/12/2016 DX Borderline resectable pancreas ductal adenocarcinoma - Stage 3 @ 61
    2/24/2016 FOLFIRINOX 3 cycles (6 infusions)
    5/12/2016 CYBER-KNIFE Stereotactic Radiation 3 sessions
    6/16/2016 WHIPPLE + portal vein and right hepatic artery reconstructions - 0/19 nodes pos - no mets. Restaged to 1A
    8/31/2016 FOLFOX for 3 cycles (6 infusions)
    Sept 2016 Know Your Tumor - PANCAN.org
    11/4/2016 CT Scan clear - NED
    May 2017 Liver lesion - DX mild fatty liver disease - NED
    Aug 2017 Several tiny lung nodules - NED
    Feb 2018 Stable lung nodules - NED
    May 2018. Lung nodules are growing; possibly mets, but still considered NED
    Aug 2018 One lung nodule has reached 1.7 cm. Pancreatic metastasis confirmed by biopsy.
    Sept 2018 Starting clinical trial with RX-3117 and Abraxane (NCT03189914)
    Nov 2028 CT-scan: Lung nodules are shrinking

  10. #10
    Moderator Senior User BrigitteM's Avatar
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    Sep 2016
    Posts
    345
    I just read in the 2018 NCCN guidelines, "“PET/CT scan may be considered after formal pancreatic CT protocol in high-risk patients to detect extra pancreatic metastases. It is not a substitute for high-quality, contrast-enhanced CT."
    __________________________________________________ ___________________
    1/12/2016 No symptoms except ongoing fatigue; blood test revealed elevated liver enzymes
    1/18/2016 Liver ultrasound, then MRI confirmed enlarged bile duct
    1/21/2016 ERCP and placement of a temporary stent
    1/28/2016 CT-Scan showed a lesion on the head of pancreas
    2/09/2016 2nd ERCP + EUS + FNA
    2/12/2016 DX Borderline resectable pancreas ductal adenocarcinoma - Stage 3 @ 61
    2/24/2016 FOLFIRINOX 3 cycles (6 infusions)
    5/12/2016 CYBER-KNIFE Stereotactic Radiation 3 sessions
    6/16/2016 WHIPPLE + portal vein and right hepatic artery reconstructions - 0/19 nodes pos - no mets. Restaged to 1A
    8/31/2016 FOLFOX for 3 cycles (6 infusions)
    Sept 2016 Know Your Tumor - PANCAN.org
    11/4/2016 CT Scan clear - NED
    May 2017 Liver lesion - DX mild fatty liver disease - NED
    Aug 2017 Several tiny lung nodules - NED
    Feb 2018 Stable lung nodules - NED
    May 2018. Lung nodules are growing; possibly mets, but still considered NED
    Aug 2018 One lung nodule has reached 1.7 cm. Pancreatic metastasis confirmed by biopsy.
    Sept 2018 Starting clinical trial with RX-3117 and Abraxane (NCT03189914)
    Nov 2028 CT-scan: Lung nodules are shrinking

 

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