Anal cancer Assessing the impact of FDG-PET in the management of anal cancer Brandon T. Nguyen a , Daryl Lim Joon a , Vincent Khoo b, * , George Quong a , Michael Chao c , Morikatsu Wada a , Michael Lim Joon a , Andrew See a , Malcolm Feigen a , Kym Rykers a , Cynleen Kai a , Eddy Zupan a , Andrew Scott d a Radiation Oncology Centre, Austin Health, Vic., Australia, b Department of Academic Radiotherapy, Royal Marsden Hospital NHS Foundation Trust and the Institute of Cancer Research, London, UK, c Radiation Oncology Victoria, Vic., Australia, d PET Centre, Austin Health, Vic., Australia Abstract Purpose: To assess the utility of FDG-PET in anal cancer for staging and impact on radiotherapy planning (RTP), response and detection of recurrent disease. Methods and materials: Fifty histopathological anal cancer patients were reviewed between 1996 and 2006. The median age was 58 years (range 36-85) with 19 males:31females. Clinical assessment with CT was compared to PET. Impact on management, disease response, recurrence and metastases was evaluated. Results: The non-PET staging was Stage I(8), Stage II(18), Stage III(22), and Stage IV(2)s. The primary was strongly FDG avid in 98% with non-excised tumors compared to CT (58%). PET upstaged 17% with unsuspected pelvic/inguinal nodal disease. Pre-treatment PET identified 11 additional by involved nodal groups in 48 patients causing RTP amendments in 19%. Post-treatment PETs at median 17 weeks (range 9–28) showed complete responses in 20 (80%) and 5 (20%) partial responses (PR). PRs were biopsy positive in 2 and negative in 3. Fifteen had follow-up scans of which all nine PETs detected recurrences were pathologically confirmed. Conclusions: Anal cancer is FDG-PET avid. PET upstages 17% and changes the RTP in 19%. PET can aid in anal cancer staging and identification of residual disease, recurrent/metastatic disease but warrants further prospective studies.  c 2008 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 87 (2008) 376–382. Keywords: Anal carcinoma; FDG-PET; Follow-up; Radiotherapy; Response; Staging Anal cancer is a relatively uncommon tumor with an inci- dence of 0.5–1.0 per 100,000 in most Western countries [1] but the incidence has almost doubled over the last 30 years and recognized risk factors include female gender and infection with HIV or human papilloma virus [2,3]. In recent years PET has been used increasingly in the management of patients with cancer, particularly for disease staging. It can result in changes to management in up to 40% of cases [4]. However, there are very few studies that have investigated the impact of positron emission tomography (PET) on anal cancer staging [5,6], radiotherapy treatment [7] and re- sponse to therapy [6,8]. Traditional staging systems based on surgicopathological parameters have been supplanted by clinical staging be- cause chemoradiation has replaced surgery as the primary treatment of choice [9]. Multivariate analysis has shown that the two most significant prognostic factors are tumor size (T stage) and nodal status (N stage) [10–12]. Accurate staging is crucial for radiotherapy treatment planning to se- lect patients with localized disease, avoid geographic miss and appropriately boost nodal disease. Approximately 10– 15% of patients experience initial failure of chemoradiation with persistent disease whilst an additional 10–30% develop tumor recurrence after an initial complete response [13– 15]. The main objective of this retrospective study was to as- sess the value of PET in pre-treatment staging of anal can- cer compared to standard clinical assessment with staging computed tomography (CT) and to investigate the impact on radiotherapy planning (RTP). Furthermore, post-treat- ment PET response was studied to determine whether it could detect persistent or recurrent disease during treat- ment follow-up. Methods and materials Study population All patients with histopathologically confirmed epider- moid carcinoma of the anus referred to the Austin Health PET Center between March 1996 and September 2006 were retrospectively reviewed. There were 50 cases and the Radiotherapy and Oncology 87 (2008) 376–382 www.thegreenjournal.com 0167-8140/$ - see front matter  c 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.radonc.2008.04.003