18F-FDG positron emission tomography staging and restaging in rectal cancer treated with preoperative chemoradiation

Int J Radiat Oncol Biol Phys. 2004 Feb 1;58(2):528-35. doi: 10.1016/j.ijrobp.2003.09.058.


Purpose: To assess the information supplied by FDG-PET in patients with locally advanced rectal cancer both in the initial staging and in the evaluation of tumor changes induced by preoperative chemoradiation (restaging).

Methods and materials: Twenty-five consecutive patients with rectal cancer were included, with tumor stages (c)T(2-4)N(x)M(0), during the period 1997-1999. We prospectively performed two FDG-PET scans in all patients to assess disease stage (1) at initial diagnosis and (2) presurgically, 4 to 5 weeks after protracted chemoradiation. Protracted chemoradiation was carried out during 5-6 weeks with 45-50 Gy, plus concurrent oral tegafur 1200 mg/day or 5-fluorouracil 500-1000 mg/m(2) administered as a 24-h continuous i.v. infusion on Days 1-4 and 21-25 of the radiotherapy treatment. Tumors were staged with CT in 95% of patients, whereas endorectal ultrasound was used in 90% of patients. Maximum standardized uptake value (SUVmax) was used as the quantitative parameter to estimate the tumor:tissue metabolic ratio.

Results: Preoperative chemoradiation significantly decreased the SUVMAX: 5.9 (mean SUVmax at initial staging) vs. 2.4 (mean SUVmax after chemoradiation) with p < 0.001. Unknown liver metastases were detected by FDG-PET in 2 patients, in 1 of them with the initial staging FDG-PET scan, and with the restaging FDG-PET scan in the other. After an average follow-up of 39 months, the value of SUVmax > or =6 allowed us to discriminate for survival at 3 years: 92% vs. 60% (p = 0.04). T downstaging (total 62%) was significantly correlated with SUVmax changes: 1.9 vs. 3.3 (p = 0.03). The degree of rectal cancer response to chemoradiation, established as mic vs. mac categories, was not associated with SUVmax differences (mean values of 2.0 vs. 2.7).

Conclusion: Preliminary results observed suggest the potential utility of FDG-PET as a complementary diagnostic procedure in the initial clinical evaluation (8% of unsuspected liver metastases) as well as in the assessment of chemoradiation response (any T downstaged event) of locally advanced rectal cancer. Initial SUVmax might be of prognostic value related to long-term patient outcome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Combined Modality Therapy
  • Female
  • Fluorodeoxyglucose F18
  • Fluorouracil / administration & dosage
  • Humans
  • Liver Neoplasms / diagnostic imaging
  • Liver Neoplasms / secondary
  • Male
  • Neoplasm Staging / methods
  • Prospective Studies
  • Radiopharmaceuticals
  • Radiotherapy Dosage
  • Rectal Neoplasms / diagnostic imaging*
  • Rectal Neoplasms / drug therapy
  • Rectal Neoplasms / radiotherapy
  • Rectal Neoplasms / therapy*
  • Tegafur / administration & dosage
  • Tomography, Emission-Computed


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18
  • Tegafur
  • Fluorouracil