A method including identifying a subject as possibly having a benign tumor in ovarian tissue and obtaining an infrared spectrum of a PBMC sample of the subject and assessing a characteristic of the sample at at least one wavenumber selected from the group consisting of: 754.0±4 cm-1, 1103.6±4 cm-1, 1121.4±4 cm-1, 1346.1±4 cm-1, 1376.9±4 cm-1, 753.50±4 cm-1, 850.5±4 cm-1, 918.9±4 cm-1, 1058.7±4 cm-1, 1187.9±4 cm-1 and 1651.7±4 cm-1. Using a processor comparing, at the at least one wavenumber, the infrared spectrum to an infrared spectrum obtained from a PBMC sample from a person without a benign tumor, to detect a difference between the infrared spectrum of the PBMC sample of the subject and the infrared spectrum obtained from the PBMC sample from the person without a benign tumor. Other applications are also described.