3DCRT, 3-dimensional conformal radiotherapy; 5-FU, 5-fluorouracil; ACT II, United Kingdom Anal Cancer Trial II; AE, adverse events; ASCC, anal canal squamous cell carcinoma; Anal cancer; BED, biologically effective dose; CFS, colostomy-free survival; CI, confidence interval; CRT, chemoradiotherapy; CTCAE v 4.0, common terminology criteria for adverse events version 4.0; CTV, clinical target volume; DM, distant metastasis; DP-IMRT, dose-painted intensity modulated radiotherapy; DVH, dose-volume histogram; G, grade; GI, gastrointestinal; GU, genitourinary; HIV, human immunodeficiency virus; HR, hazard ratio; IMRT; IMRT, intensity modulated radiotherapy; IQR, interquartile range; LN, lymph node; LR, local recurrence; LRR, locoregional recurrence; MMC, mitomycin-C; OS, overall survival; PFS, progression-free survival; PTV, planning target volume; RT, radiotherapy; RTOG, Radiation Therapy Oncology Group; Radiation