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

Abstract

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.

Anal cancer FDG-PET standard uptake value: correlation with tumor characteristics, treatment response and survival

“…At this time, the two most significant prognostic factors are tumor size and nodal status related to the TNM stage [10,11]. (18) F-fluorodeoxyglucose positron emission tomography/CT (FDG-PET/CT) has an important role in staging and treatment planning of various tumor locations [12][13][14] and may provide diagnostic useful information also for the anal canal cancer [15][16][17][18][19]. The recently updated European Society for Medical Oncology…”

Anal Carcinoma: A Series of Cases with a Literature Review

“…There are different opinions about the tumor size which is considered to be adequate for a local excision: some say it is 2 cm in diameter (T1), while others consider 7 mm in diameter with the excision into the healthy tissue of 3 mm. In case of a recurrence -18%-63% (45) or a positive margin, both a re-excision and an additional CRT are recommended (5).…”

“…Computed tomography (CT) and magnetic resonance imaging (MRI) can occasionally be used for the evaluation of lymph nodes, as well as lymphnode biopsy (SLNB) or PET scan, (5) and palpation of the inguinal and abdominal lymph node. MSCT is a better solution compared with the abdominal or X-ray imaging.…”

Cancers of the Anal Canal: Diagnosis, Treatment and Future Strategies

“…The vast majority of anal cancers are fluorodeoxyglucose avid [61]. The additional information gleaned from the PET/CT includes the volume of the primary tumor, increased uptake of inguinal, mesorectal and internal iliac lymph nodes, and increased uptake in more distant nodes and metastases.…”