Image analysis of microvessel surface area predicts radiosensitivity in early-stage laryngeal carcinoma treated with radiotherapy

Purpose: The tissue oxygenation level, which is theoretically governed by d istance from blood vessels, is one of the most important modulators of the radiosensitivity of carcinoma. A computed image analysis system for the det ection of tissue oxygenation was developed to establish a method of predict ing radiosensitivity in early-stage laryngeal carcinoma treated by curative radiotherapy. Experimental Design: Microvessel structures labeled with CD31 antigen were investigated in 55 patients undergoing curative radiotherapy for T-1 and T- 2 laryngeal carcinoma. We calculated (a) microvessel density [(MVD) vessels /field] under a microscope; (b) the ratio of the total microvessel number ( TN):tumor area (TA) [TN:TA; vessels/mm(2)]; (c) the ratio of the total micr ovessel perimeter (TP):TA (TP:TA; mm/mm(2)); and (d) the ratio of tumor tis sue area > 150 mum from microvessels (hypoxic ratio; %) as parameters of ti ssue oxygenation in each whole biopsy specimen by using an image analyzer. We compared each of these factors with radiosensitivity. Results: Mann-Whitney's U test revealed that tumors with a high MVD (median , 42 vessels/field), high TN:TA ratio (median=40.9 vessels/mm(2)), high TP: TA ratio (median, 2.92 mm/mm(2)), and low hypoxic ratio (median, 30.3%) had significantly greater radiosensitivity than tumors with a low MVD, low TN: TA ratio, low TP:TA ratio or high hypoxic ratio (P = 0.002, P = 0.0004, P < 0.0001, and P 0.004, respectively). Conclusions: Prediction of radiosensitivity on the basis or the TP:TA ratio can be used as an efficient means of avoiding ineffective radiation, compl ications after salvage surgery, and prolonged hospital stays.