For many years, cancers of many different types have been treated routinely with chemotherapy. Chemotherapy is a drug treatment used primarily to destroy cancer cells within the body. Although chemotherapy can be a vital treatment in cancers that have spread to different areas of the body other than the initial tumour site (secondary and tertiary cancers), there is a downside to this treatment option. Chemotherapy drugs like Cisplatin are known for being non-selective drug treatments – in that they kill cancer cells along with other normal human cells. Whilst in the past this process was accepted, advancements in technology have permitted a refinement in techniques. Indeed, chemotherapy may not work for certain types of cancer, and could potentially shorten the lifespan of an individual with cancer, who may gain a better quality of life from abstaining from treatment.
Whilst a lot of chemotherapy treatments are useful for cancers that are spread, the drugs have quite severe side effects and can permanently damage tissues and organs in the body – namely the liver, kidneys and lungs. In oncology care, diligence is given to weighing up the pros and cons of treatment before any chemotherapy or radiotherapy regimen is undertaken. So how is it clear if chemotherapy is stopping the progression of cancers? In the past, chemotherapy treatment and medical diagnostics were not as widely available and the imaging was more rudimentary, meaning a course of treatment may have to be undertaken for 6-8 weeks before follow up imaging. The follow up imaging could display changes in tumour size, control of metastases and potentially further spread of the cancer, yet at this point normal body tissues may have been compromised from chemotherapy treatment. Alongside this, the patient may have also had a reduced quality of life in the time between imaging sessions, meaning a potentially ineffective drug may have been doing more harm, wasting time and money on treatments.
However, a recent advancement in cancer imaging using PET (positron emission tomography) scans for more cancers has allowed a more acute use of chemotherapy towards personalised medicine whereby the effectiveness of a regimen can be assessed in days, not weeks. Previously, PET scans were only used in easier to detect cancers like lymphoma, which is easier to detect due to the characteristics of the cancer and the tissues it inhabits. A study from the Imperial school of Medicine recently theorised that PET scans could be used to detect secondary cancers in kidney, bowel, breast and pancreatic cancers using a different form of PET.
So how does a PET scan work? A serum or trace element is injected into the body (normally into a vein or artery) which is up taken quickly by cancer cells. When examined using scanning equipment, cancer cells and tumours can be distinguished quickly from normal body cells. In previous cancer technology, this was employed but metastases in the liver were often neglected as the hepatic cells took up a large proportion of the trace alongside cancer cells. This proved hard to distinguish the liver cells and cancer cells, thus leaving question marks around the efficacy and prevalence of metastases, risking a non-response to treatment. In this age of personalised medicine, patients in the study were given chemotherapy regimens and scanned in much shorter intervals (3-5 days) post treatment to ascertain the effectiveness of the chemotherapy. Thus, if the treatment to had begun work, cancer cells would be fewer in the PET scan, showing a good response to treatment. If no real changes had occurred, the clinicians deduced a different regimen may be used, or the metastases may have advanced to an untreatable stage.
What implications does this have for future cancer care? Fewer patients will be exposed to chemotherapy for a shorter duration of time, as well as improving the specificity of drug treatments to patients – minimizing side effects and improving their quality of life. In the absence of blindly following a treatment regimen, clinicians may learn which drugs work best for each cancer at different stages, as well as potentially increasing the survival rate and chance of remission through early detection. Furthermore, new innovations in PET scanning techniques have allowed a greater look at the characteristics of tumours, with a focus on the detection and monitoring of internal tumour growth or shrinkage.
What is the takeaway? Clinicians may be able to give one dose of chemotherapy to patients, monitor the cancer progress or cessation and then make informed decisions on the next best treatment option. This can prevent unnecessary treatments and improve the quality of life of patients without the side effects of treatment which may be unsuitable for them.