 The study identifies diminutive primary-grace tumor volume, PGTV, and distance from the anal verge as independent predictors of superior tumor response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer patients, and also reveals that PGTV is an independent predictor of pathologic complete response. The study further shows that patients with diminutive PGTV have a longer disease-free survival than those with giant PGTV.