The role of FDG-PET in the design of the radiation fields for patients with advanced esophageal cancer

The impact of 18-fluorodeoxyglucose positron emission tomography on the staging, management and outcome of anal cancer

Accurate inguinal and pelvic nodal staging in anal cancer is important for the prognosis and planning of radiation fields. There is evidence for the role of 18-fluorodeoxyglucose positron emission tomography (FDG-PET) in the staging and management of cancer, with early reports of an increasing role in outcome prognostication in a number of tumours. We aimed to determine the effect of FDG-PET on the nodal staging, radiotherapy planning and prognostication of patients with primary anal cancer. Sixty-one consecutive patients with anal cancer who were referred to a tertiary centre between August 1997 and November 2005 were staged with conventional imaging (CIm) (including computed tomography (CT), magnetic resonance imaging, endoscopic ultrasound and chest X-ray) and by FDG-PET. The stage determined by CIm and the proposed management plan were prospectively recorded and changes in stage and management as a result of FDG-PET assessed. Patients were treated with a uniform radiotherapy technique and dose. The accuracy of changes and prognostication of FDG-PET were validated by subsequent clinical follow-up. Kaplan–Meier survival analysis was used to estimate survival for the whole cohort and by FDG-PET and CIm stage. The tumour-stage group was changed in 23% (14 out of 61) as a result of FDG-PET (15% up-staged, 8% down-staged). Fourteen percent of T1 patients (3 out of 22), 42% of T2 patients (10 out of 24) and 40% of T3–4 patients (6 out of 15) assessed using CIm, had a change in their nodal or metastatic stage following FDG-PET. Sensitivity for nodal regional disease by FDG-PET and CIm was 89% and 62%, respectively. The staging FDG-PET scan altered management intent in 3% (2 out of 61) and radiotherapy fields in 13% (8 out of 61). The estimated 5-year overall survival (OS) and progression-free survival (PFS) for the cohort were 77.3% (95% confidence interval (CI): 55.3–90.4%) and 72.2% (95% CI: 51.5–86.4%), respectively. The estimated 5-year PFS for FDG-PET and CIm staged N2-3 disease was 70% (95% CI: 42.8–87.9%) and 55.3% (95% CI: 23.3–83.4%), respectively. FDG-PET shows increased sensitivity over CIm for staging nodal disease in anal cancer and changes treatment intent or radiotherapy prescription in a significant proportion of patients.

Positron Emission Tomography for pretreatment staging and posttreatment evaluation in cancer of the anal canal

PURPOSE

In recent years, combined modality therapy (CMT) with chemotherapy and radiation has replaced surgery as the preferred treatment for cancer of the anal canal. Clinical staging with computed tomography (CT) scan alone may underestimate the extent of disease. We investigated the utility of positron emission tomography (PET) with 2-deoxy-2[F-18]fluoro-D-glucose (FDG) in the staging and determination of response to CMT.

PATIENTS AND METHODS

From September 1999 to August 2002, 21 patients with cancer of the anal canal were studied prospectively. All patients underwent pretreatment PET, in addition to standard clinical evaluation that included CT scanning. Follow-up PET studies were ordered one month after completion of CMT.

RESULTS

Sites of metastases not observed on CT scan were identified in five of 21 patients (24%). These sites included pelvic lymph nodes (four patients) and distant omental metastasis (one patient). In another patient, PET confirmed the presence of suspected M(1) disease in the liver. Posttreatment PET imaging was less useful. Nine patients had minimal residual PET activity at the primary site on the one-month follow-up PET study, but only three of these subsequently developed local recurrence. In addition, recurrences occurred in three patients (two local, one distant) of the six who had negative posttreatment PET studies.

CONCLUSIONS

FDG-PET, in conjunction with CT scanning, provides additional staging information in cancer of the anal canal. This information may have implications for prognosis and radiotherapy planning. Posttreatment PET scans appear to be of little value in predicting durability of response.