Bowel cancer symptoms: What are the signs to look out for?
Written in association with:
Clinical oncologist
Published: 04/05/2023
Edited by: Sophie Kennedy
In this informative guide to the symptoms of bowel cancer, revered consultant clinical oncologist Dr Nick MacLeod reveals the signs which can indicate bowel cancer and details the associated risk factors. The highly experienced specialist additionally sheds light on the most common treatment modalities for cancers of this type.
What are signs the signs of bowel cancer?
Firstly, it’s important to mention the bowel screening programme which helps to detect bowel cancer before patients become symptomatic. I certainly encourage anybody who is eligible for bowel screening to ensure that they comply so that any cancers can be picked up as early as possible.
There are various different signs that can be associated with bowel cancer. The symptoms a patient experiences often depend on whereabouts in their bowel the cancer is. If the cancer is in the left side of their colon or in the rectum, patients are more likely to symptoms along the lines of rectal bleeding or a change in bowel habit towards constipation or diarrhoea. Additionally, patients can experience urgency symptoms, known as tenesmus, where they have the sensation that they need to open their bowels but then nothing happens. In these cases, it is the tumour which gives this symptom.
Bowel tumours on the right side of the colon tend to present often more insidiously with tiredness and weakness, with some patients being fatigued. These patients are often found to be anaemic and further investigations may detect the bowel cancer. Patients can also present with abdominal pain, sometimes as an emergency with severe symptoms of pain, vomiting, or constipation.
There are a variety of different symptoms that can be associated with bowel cancer and you should see your doctor about any changes you notice. It’s important to stress that not all patients who have bleeding or a change in bowel habit necessarily have bowel cancer, but these are certainly the sort of symptoms that we would be concerned about and require investigation.
Which factors can raise a person’s bowel cancer risk?
There are various different factors which can increase the risk of bowel cancer. We know that approximately ten per cent of bowel cancers are hereditary and these tumours tend to affect several family members of each generation. Other conditions, such as Crohn's disease or ulcerative colitis, are known to be associated with higher risks of bowel cancer.
In terms of other risk factors, a diet which is low in fibre and high in red meat, particularly processed meat, can increase your risk of bowel cancer. Therefore, I generally encourage people to try and have a healthy balanced diet.
In addition, being significantly overweight is a recognised risk factor for bowel cancer. Excess alcohol consumption and smoking are less significant risk factors but can also be associated with bowel cancer. A healthy balanced diet with regular exercise is good for you for a number of reasons, including reducing your risk of bowel cancer.
Which treatments are available for bowel cancer?
There are lots of different treatments for bowel cancer. If the tumour is found very early, sometimes at the time of the colonoscopy, the endoscopist can see a small polyp which can be excised at that time. In some cases, that is all the treatment that is needed.
For larger tumours, a bigger operation, such as having part of the bowel removed, can be required. This usually requires an inpatient hospital stay for a few days. Following these operations, some patients require what we call adjuvant chemotherapy, which is chemotherapy given to reduce the risk of the cancer recurring.
In addition, some rectal cancer patients may undergo neoadjuvant treatment which is given before definitive surgery. This is usually in the form of radiotherapy or chemotherapy, although some patients may also potentially benefit from immunotherapy.
In more advanced cancers where there is evidence of the cancer having spread (metastasized) to other parts of the body, then we have a variety of different treatments which may be indicated. Although this is mainly chemotherapy, sometimes patients undergo targeted therapies and immunotherapy. The decision about which treatment we would give to each patient depends on different factors - both patient related factors, such as how fit the patient is, as well as tumour related factors, including the molecular profile of the tumour and which medicines are potentially going to be more active against that specific cancer.
There are a huge number of drugs available to us and many have emerged in the last few years. It's a very exciting time to be involved in bowel cancer treatment.
Can bowel cancer be prevented?
In terms of preventing bowel cancer, the main preventative measures are indicated in patients who have significant family histories of bowel cancer. For those who carry a genetic risk, prophylactic surgery may be offered to the remove part or the whole of the colon before a cancer develops due to the significantly high risk of those patients developing cancer.
Otherwise, we don't really have strategies to prevent bowel cancer, but what we can do is try to reduce the risk much as possible. As I mentioned earlier, there are several lifestyle factors related to bowel cancer risk, including eating a healthy balanced diet, taking regular exercise and trying to make sure we're not overweight. For those looking to reduce their risk of bowel cancer, I would strongly encourage them to do so by addressing these factors.
You can read more about how radiotherapy is used in the treatment of bowel cancer in Dr MacLeod's other informative article on the condition.
If you are concerned about a family history or symptoms of bowel cancer, you can schedule a consultation with Dr MacLeod by visiting his Top Doctors profile.