One of my best memories of Georgie is a weird one. He was undergoing photodynamic therapy (PDT) at the UCH Teenager Cancer Unit and I went to visit him there after work. Whilst he was having the treatment he couldn’t be exposed to light so we had to sit in the dark. We ate dinner in relative darkness and spent the evening just me, him and my Uncle Pan. I like to talk to my Uncle about all things politics and that sort of thing whilst Georgie and I had a shared love of One Tree Hill and we all support Chelsea FC so there was no shortage of things to talk about. It was actually one of my favourite evenings and I always think of it when I think of Georgie.
I’m going to focus on PDT today and I hope this post provides you with some interesting information about a treatment option which is not yet as well known as others such as chemotherapy.
PDT is a treatment mostly used for non melanoma skin cancer cases but it can also be used to treat other cancer types. It is also known as photo radiation therapy, phototherapy and photo chemotherapy. It combines a drug, known as a photosensitizer, which makes cells sensitive to light and exposure to a particular type of light. There are different types of photosensitizing agents and each is activated by a light on a specific wavelength. Different types are used to treat different body parts.
The sensitizing drugs produce a type of oxygen that is able to kill nearby cells when they are exposed to their particular light. This directly kills cancer cells and may also be able to shrink and destroy tumours in other ways, possibly by damaging the blood vessels in the tumour to prevent it receiving the nutrients it needs to survive. PDT may also possibly trigger the immune system so it can attack the cancer cells. It can be used as part of a combination of treatment with surgery, chemotherapy, radiotherapy or biological therapy.
Treating Skin Cancer with PDT
PDT is sometimes used to treat cases of non melanoma skin cancer. A cream containing the light sensitive chemical is applied to the skin cancer and surrounding area, although it can also be used in tablet or injection form. A strong light is shone on the area for up to forty five minutes once the chemical has been absorbed and the light kills any cell that has absorbed the drug.
Treating Other Cancer Types with PDT
Research indicates that PST may be able to treat some cancer types that are found inside the body. It is mainly used to shrink larger tumours that are blocking the airway or food pipe and it can also be used to treat cancers found in the head and neck area, the oesophagus, and on the lining of internal organs. Georgie has osteosarcoma of the mandible (jaw) and PDT was used for this. The light used for PDT can only pass through about 1cm of tissue and can be used to relive symptoms and help the patient breath or swallow better. It can be used to treat patients in the very early stages of lung cancer or oesophageal cancer if the patient is not well enough to have surgery or chemotherapy.
For internal cancers, the light sensitizing drug is injected into your blood stream, normally via a cannula. Cells all over the body absorb the drug but it usually lasts longer in cancer cells so about two or three days after receiving the chemical, a light will be shone to activate the drug usually via an endoscope. You may need local or general anesthetic as the laser light is switched on when the tube reaches the cancer.
Your skin and eyes may be sensitive to light for up to six weeks after the treatment due to the light sensitizing drugs used. Direct sunlight and bright indoor light will need to be avoided for around six weeks after the therapy and skin may become very sensitive if it is exposed to light around this time period. PDT can cause some burns, swelling or scarring to nearby healthy tissue. Other side effects can include coughing, difficultly swallowing, stomach pains, and breathlessness but this is usually temporary.
I hope you have found this informative. I know it sounds scary but it did seem to help Georgie whilst he was having it. To find out more, please visit www.cancerresearchuk.org