Gerald Fogarty PhD FRANZCR

Radiation for cancers of the skin

Cancers that can be treated with radiation include basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), Melanoma, Merkel Cell Carcinoma (MCC), Lymphoma and a range of rarer tumours such as malignant fibrous histiocytoma (MFH) etc.

BCC and cSCC are sometimes called keratinocytic cancers as they both come from the same cell, the keratinocyte.

All skin cancers that are not melanoma can be described by the term non-melanoma skin cancers or NMSC, but this term is being phased out.Invasive disease is capable of spreading to other organs. The mode of spread can be by local invasion into other organs. This is the usual mode of spread for BCC. It can be by perineural invasion. It can be by lymphovascular space invasion, spreading to nearby lymph nodes, and then into the rest of the body.

Some cancers have a non-invasive phase, also called an in-situ phase. cSCC has various names for its in-situ stage, which include in-situ cSCC, Bowens Disease and intraepithelial carcinoma, they are really all the same thing. Melanoma also has various names for its in-situ stage which include in-situ melanoma, Hutchinson Melanotic Freckle (HMF) and Lentigo Maligna, again really all the same thing. Adenocarcinoma of skin has as its in-situ phase extramammary Paget’s disease (EMPD). The non-invasive phase is considered dangerous as it can progress to invasive disease.

Radiation can be used for benign conditions of the skin

These are not cancer but are troublesome because they have a population of cells that divide regularly when they should not, causing symptoms. Radiotherapy is effective because it slows the pace of cell division.

Benign conditions include Rosacea, Keloid, Psoriasis, Extramammary Pagets Disease (EMPD), hidradenitis suppurativa (HS), Disseminated Superficial Actinic Porokeratosis (DSAP) can be treated with radiotherapy.

Intention of radiation treatment – Definitive, Adjuvant and Palliative treatment settings

Definitive treatment is when radiation is the main treatment. It is usually used alone to cure.

Adjuvant radiation is when radiation is used as a guarantee following another therapy that has unexpectedly not worked well eg RT after surgery when the surgery has not cleared all the cancer.

Palliative treatment is when RT is used to reduce symptoms such as pain, bleeding, the need for dressings, and smell. It stops the cancer having such a great impact on function and cosmesis.