Spontaneous tumour regression

Sammanfattning: Complete tumour regression is the optimal outcome of cancer therapies. There are however types of tumours that naturally regress. Most of these are benign, dermatological and have an early onset in life. This literature study aims to elucidate the mechanisms behind spontaneous tumour regression. In Libechov Melanoblastoma-Bearing minipigs, an animal-model specifically bred to develop malignant melanoma, the tumours usually involute within three months. This has been proven to be the effect of a lymphocytic infiltrate, predominated by cytotoxic T-cells. An epidermotropic myeloid tumour of Langerhans cell origin, frequently seen in young dogs, is called histiocytoma and is known to have a very brief proliferation followed by a quick remission. The involuting process is due to extensive lymphoid infiltrate. In hemangioma, rapid growth of the tumour is followed by a regressing stage that has been linked to apoptosis, possibly induced by mast cells. As in the case of hemangioma, infantile mastocytomas are known to regress before the child reaches puberty. The series of events behind the remission remains poorly investigated, but is thought to be connected to increased apoptosis of tumour cells. Another self-involuting tumour of the skin is the virus-induced papilloma, which self-keratinizes to oblivion. The infected cells become terminally differentiated and thus lose their ability of mitosis. There appears to be no overall explanation as to why and how spontaneous tumour regression occurs, but different types of tumours seem be unique from one another.