PET after Chemotherapy in Rhabdomyosarcoma Connective Tissue Oncology Society November 19, 2005

1. PET after Chemotherapy in RhabdomyosarcomaConnective Tissue Oncology SocietyNovember 19, 2005 Michelle L. Klem, Leonard H. Wexler, Ravinder Grewal, Heiko Schoder, Paul A. Meyers, Suzanne L. Wolden Memorial Sloan-Kettering Cancer Center

2. Background • Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood. • Staging system is clinical and radiographic. • PET for initial staging • Identify involved LN, distant metastases • Determine involvement of CT/MRI equivocal sites

3. PET at Diagnosis Chest wall embryonal RMS (SUV 5.1) Supraclavicular LN (SUV 2.8)

4. Hypothesis • Initial treatment will result in a decreased SUV at the primary site of disease • Study design- retrospective review of RMS patients who had PET scans at diagnosis and after receiving initial therapy

5. Methods • PET scans performed on • Biograph PET/CT scanner (Siemens) • Discovery LS PET/CT scanner (General Electric) • GE ADVANCE PET scanner (General Electric) • SUV at primary, regional, distant sites, and areas of clinical suspicion • Scans obtained 1 hour after iv 18F-FDG

6. Patient Characteristics • All patients with RMS treated at MSKCC from 2/02 till 12/04 were reviewed • 20 had PET at the time of diagnosis and after receiving chemotherapy • 11 patients had PET prior to any chemo • 9 patients within first cycle of chemotherapy (13 days)

7. Patient Characteristics • 13 females, 7 males • Median age 12.3 years (range 2-38 years) • 10 embryonal, 10 alveolar • Stage • Stage II: 1 • Stage III: 14 • Stage IV: 5 • Group • Group 3: 15 • Group 4: 5

8. Primary Site

9. Treatment Prior to PET • All patients received 2-8 cycles of chemotherapy prior to follow up PET • 5 patients completed radiation prior to PET

10. Rapid Response of PET to Chemotherapy

11. Rapid Response of PET to Chemotherapy

12. Initial SUV *p=0.006

13. Results • First follow up PET • median of 2.8 months after chemotherapy (1.3-7.3m) • median of 4 cycles of chemotherapy • 18 patients had a decrease in SUV • Median decrease 3.7, range (0.2-11.7)

14. Results • 12 patients with normal PET by first follow up • 3 had completed radiation • 18 had eventual normalization of PET • No correlation of early normalization of PET with • primary site of disease, histology, stage, group • gender, age at diagnosis • SUV at diagnosis

15. Time to Normalization

16. Pathologic correlation

17. Response on PET 3 year old boy with alveolar RMS in the gluteal and pelvic regions

18. Response on PET Irinotecan/ Carboplatin 3 year old boy with alveolar RMS in the gluteal and pelvic regions

19. Response on PET 14 year old female with an alveolar paranasal RMS

20. Response on PET Irinotecan/ Carboplatin 14 year old female with an alveolar paranasal RMS

21. Conclusions • PET has potential utility in monitoring response to treatment. • SUV at primary site is higher when initial PET is prior to therapy. PET should be performed prior to chemotherapy when possible. • A decrease in SUV was seen with therapy. • Most patients had normalization by first follow up PET. • Normalization of PET correlated with pathologic response to therapy. • Further work is needed to assess if response on PET can be used to guide therapy and predict response in RMS.