Managing Drug Treatment Side-Effects

Everyone's response to taking drugs is different but in this section we highlight some of the common side-effects. For most people these are manageable and nothing like the serious side-effects of conventional chemotherapy. This is mainly because the drugs are targeted at a particular chemical process in the body whereas conventional chemotherapy acts by attacking all rapidly dividing cells in the body. Of course, cancer cells are dividing rapidly, but then so are many other types of non-cancer cells. An example of this would be the cells providing hair growth, hence the familiar loss of hair during chemotherapy. Some people have to take specific measures to cope with the side-effects they experience and a very few may need to reduce the drug dose or stop taking drugs altogether.  Always discuss your side-effects with your oncologist, keeping a formal record can help with this.

Imatinib is a local irritant and the reason for the instruction on the packs "Take with a large glass of water" is to minimise the irritant effect on your digestive system.

Imatinib does have side-effects although for many people these seem to diminish with time (or maybe one just gets used to them).  Patients do report that there is some difference between the side-effects experienced by different makes - so if you experience severe side-effects ask if you can change to another brand.  Common issues reported by GIST Cancer UK members are reported below and further details of typical side-effects can be found on the Cancer Research UK website.

Everyone experiences some tiredness and fatigue, at least at first. This was the most common side-effect in a survey of about 200 GIST patients undertaken by the Life Raft Group. In many patients, this fatigue may still be the effect of abdominal surgery, as well as the effect of Imatinib.

Everyone seems to experience the strange side-effect of "puffy eyelids" and some eye-watering. This is a weird effect, considering where the drug is targeted, but it does ease with time in most patients and is usually not painful.

It is quite common to get digestive upsets of various kinds, most commonly wind ("gas" in the US) and the associated discomfort that goes with this. Some patients are affected by diarrhoea. These digestive upsets are most troublesome in patients who have had part (or all) of their stomach removed because of the position of the original GIST. These effects can often be mitigated by taking the drug with food and a large glass of water.

There are a variety of rather surprising effects associated with skin and body hair. Some patients experience rashes and skin roughening which is helped by skin creams and anti-itch prescriptions. Body hair seems to turn brittle and be easily rubbed off by clothing. Quite a few (mainly male) patients have reported that their head hair has darkened from grey and there are a few cases of hair re-growth on bald patches(!).

There is a feeling that imatinib causes reduced blood pressure, so if medication is being taken for hypertension, one's GP must be aware of this and not lower the blood pressure too much by the combination of drugs.

A few reports indicate that imatinib may be effective in reducing blood cholesterol levels, so again your GP should check this.

Another side effect, which is rare but potentially serious, is accumulation of fluid in the body - particularly in the abdominal cavity. This is called Ascites. It seems to happen occasionally after liver surgery. It can usually be treated with diuretics, but sometimes the fluid has to be drained.

Sunitinib (trade name Sutent) is a tyrosine kinase inhibitor used where tumours are resistant to imatinib or for those who cannot tolerate the drug. Sutent has been proved to be a valuable drug for GIST patients, increasing the average overall survival. There is evidence that patients who have Exon 9 mutatons, or Wild-type GIST tend to respond better to Sutent.

In most patients the side-effects are more noticeable than those for imatinib. Some patients have to change the way they take the drug, or take a lower dose.  If you experience severe side-effects then discuss this with your oncologist. Further details of typical side-effects can be found on the Cancer Research UK website.

The most commonly reported side-effects include "hand-foot syndrome" (where hands and feet become very sore), diarrhoea, skin discoloration, mouth irritation, weakness, and altered taste. Some patients also experience fatigue, high blood pressure, bleeding, swelling, and taste disturbance. Hypo-thyroidism was also observed.

Pfizer, the manufacturer, has produced an information booklet for patients taking the drug. This gives guidance for managing side-effects, and should be given to every patient by their oncologist before they start taking the drug.

Regorafenib (Stivaga) is the standard third line treatment for GIST patients in England, Scotland and Wales. If you live in Northern Ireland your doctor can apply to your local Health and Social Care (HSC) Trusts through the Individual Funding Requests (IFR) process.

There are few patients taking this drug and side-effects are personal.  You can find out more about the general nature of those reported on the Cancer Research UK website.