The invention relates to the field of medicine, more particularly oncology, and can be used for inhibiting the growth of malignant neoplasms irrespective of the histogenesis and site thereof. The method comprises irradiating various areas of the brain with monochromatic light of low intensity in the near-UV region of the spectrum. The laser light is delivered to various areas of the brain by invasive and non-invasive methods. For the non-invasive method, the cranium fontanel or the nose ethmoid is used. In the case of the invasive method, special optical implants are used which pass through openings made in the cranium. Experimental animal models demonstrated a significant increase in the lifetime of animal tumour-bearers after the laser irradiation of certain areas of their brains, irrespective of the site of the malignant neoplasm and the histogenesis thereof.