Maria De Santis, MD

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Maria De Santis, MD Kaiser Franz Josef-Spital,
Vienna Center for Oncology and Hematology and
LBI-ACR and ACR-ITR VIEnna
The role of PET after chemotherapyEIS on
Testicular Cancer,Munich, May 15, 2008
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Fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) PET

• Many neoplasms have an enhanced glucose
  metabolism compared to normal tissue.
• FDG provides functional data on tumor
  metabolism, complementary to morphologic imaging
  studies.
• Standard tool for decision making in lymphoma,
  Hodgkins disease, different solid tumors post
  chemotherapy.
• Germ cell tumors (GCT) are characterized by a
  high FDG uptake.

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Limitations of FDG PET

• False positive results, Immanent

• Inflammatory, granulomatous tissue (sarcoidosis)
• Phagocyte and macrophage activity in necrotic
  tissue lt 2- 4 wks after chemotherapy
• Hyperplastic bone marrow (with or without
  stimulation by growth factors)
• Thymic uptake after chemotherapy in young adults
  (lasting up to 2 years)
• Metabolic flare within first 2- 4 days after
  chemotherapy

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Limitations of FDG PET

• False positive results, man-made

• - Inadequate clinical correlation
• - Inadequate interpretation of physiologic
  uptake

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Limitations of FDG PET

• False negative

• 2 weeks after chemotherapy, tumor- and
  treatment specific
• Limited resolution in lesions lt5mm(possible
  positivity of extremely active lesions 5-10mm)
• Mature teratoma,negative result expected

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FDG PET and the teratoma dilemma
Differences in the kinetic rate constants of FDG
uptake between mature teratoma and
necrosis/fibrosis, based on kinetic modeling
(n6). Sugawara Y et al , Radiology
1999211249-56
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FDG PET in non-seminomatous postchemotherapy
residuals
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18F-FDG-PET in Germ Cell Tumors following
Chemotherapy Results of the German Multicenter
Trial
Statistical plan estimate of gt70 accuracy for
PET
M. De Wit, ASCO 2006, abstract 4521
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PET in postchemotherapynon-seminoma residuals

• False positives due to inflammation
• False negatives due to teratoma or small lesions
• High PPV in poor prognosis or relapsed patients
  after high dose-chemotherapy
• Strict timing of PET after chemotherapy is key

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PET in postchemotherapynon-seminoma residuals
Conclusion

• Resection of postchemotherapy NSGCT residuals
  continues to be mandatory.
• In poor prognosis and relapse-patients after
  HD-chemotherapy, PET might be helpful for
  decision making.
• Further prospective trials are needed to explore
  this indication of PET.

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The management of postchemotherapy seminoma
residuals is controversial

• Surgery for lesions gt3.0 cmR Motzer JCO 1987, H
  Puc JCO 1996, HW Herr J Urol 1997
• ObservationSM Schultz JCO 1989, A Horwich Ann
  Oncol 1997
• (Radiotherapy)GM Duchesne EJC 1997

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Postchemotherapy surgery of pure seminoma lesions
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Rationalefor FDG PET in seminoma residuals
The presence of teratoma is negligible.
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FDG PET in postchemotherapy seminoma residuals
CHT-PET timing not stated, old PET technique
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FDG-PET in Seminoma-Residuals (SEMPET)Austrian-
German Multicenter Trial
De Santis et al, JCO 2004

• n 56 PET studies in 51 patients
• Median follow-up 32 months
• Key inclusion criteria gt 1 cm Ø
• PET scheduled 4-12 weeks post chemotherapy
• 8 positive PETs all with viable tumor or
  clinical relapse
• 48 negative PETs 2 false negative,
  46 correctly negative

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RESULTS of CT
SEMPET trial, JCO 20004
37
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Fisher's exact test plt0.026
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FDG PET-result correlated to
largest residual lesion
SEMPET trial, JCO 20004
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Final results of FDG PET and CT
SEMPET trial, JCO 20004
Abbreviations CI, Confidence intervals at
confidence level (1-?) 0.95
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Conclusion 1

• FDG PET can contribute to the management of post
  chemotherapy seminoma residuals in avoiding
  unnecessary additional therapy in patients with
  lesions gt 3cm.

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Conclusion 2

• FDG PET continues to be a good predictor of
  viable tumor in postchemotherapy seminoma
  residuals.

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Conclusion 3

• PET is a new standard of care

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EGCCCG Consensus 2007 on postchemotherapy
seminoma residuals
Krege, et al Eur Urology 2007

• No resection or any other treatment modality is
  necessary in patients with a negative PET scan,
  whereas a positive PET scan, if performed gt46
  weeks after day 21 of the last chemotherapy, is a
  strong and reliable predictor of viable tumour
  tissue in patients with residual lesions EBM
  IIB. In patients with positive FDG-PET,
  histology should be obtained by biopsy or
  preferably by resection.

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Thank you!