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.
Photodynamic
Therapy
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
xxx
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