What is Cancer?
Cancer is a disease that affects cells in the human body. Cancer develops when abnormal cells begin to grow uncontrollably. These abnormal cells can then grow onto surrounding tissues, damaging them, or can travel to other parts of the body which causes more damage.
In 2020 alone, it is estimated that 145,483 cancer cases were diagnosed in Australia, with 68,754 of these being in females and 76,729 in males.
The top five most common cancers in Australia (not including non-melanoma skin cancers) are breast cancer, prostate cancer, melanoma, colorectal (bowel) cancer and lung cancer, and make up to approximately 60% of all cancers diagnosed in Australia.
Figure 1. Estimated most common cancers diagnosed, 2020, Cancer Australia
Most types of cancer start off in a specific part of the body as a tumor, known as the primary site or primary tumor. Tumors can either be benign (non-cancerous) or malignant (cancerous).
These tumours don’t spread to other parts of the body and stay within their regular boundary, although if left unchecked, some have the potential to grow into a cancerous tumour. Other benign tumours aren’t able to develop into cancerous tumours. If a benign tumour continues to grow in its original site, it may impact surrounding organs by pressing into them.
Malignant tumours are built up of cancer cells. When they first develop, they may be confined to their original site, known as a cancer in situ (or carcinoma in situ). If left untreated, these cells may break away from their site and spread into surrounding cells and tissues, becoming invasive cancer.
Cancer is sometimes spread by the cancerous cells breaking off of the primary tumour, entering the lymphatic system or bloodstream and spreading to a new organ, creating a secondary tumour site.
What are the different types of cancer?
There are numerous kinds of cancer that affect all different parts of the body. They are named for the organ or type of cell that the cancer affects. For example, brain cancer starts in the brain, skin cancer in the skin and bowel cancer in the bowels.
The types of cancer can be split into several different categories:
- Carcinoma: cancer that begins in tissues that line or cover internal organs or in the skin. For example, melanoma
- Sarcoma: cancer that begins in fat, blood vessel, muscle, bone, or other supportive or connective tissue in the body. For example, osteosarcoma
- Leukaemia: cancer that begins in the tissues that create blood cells, such as the bone marrow. For example, acute myeloid leukaemia
- Lymphoma and myeloma: cancers that start in cells of the immune system. For example, Hodgkin lymphoma and multiple myeloma
- Central nervous system cancer: cancer that begins in the spinal cord or brain. For example, glioma.
What are the symptoms of Cancer?
The symptoms of cancer vary, depending on where the cancer is in the body and how developed it is. Cancer symptoms are often caused by other means such as benign tumours, injury, illness or other conditions. If experienced symptoms aren’t getting better after a few weeks, see a doctor so that the symptoms that arise may be treated as soon as possible. On the other hand, cancer may not display any obvious symptoms such as pain or discomfort, so it is advised not to wait for pain to arise to see a doctor.
Some symptoms for some of the most common types of cancer include:
- Lumps or firm feelings in breast tissue
- Nipple discharge and changes
- Itchy, dimpled, puckered, scaly or red skin
- Trouble or pain when urinating
- Blood in urine
Bleeding or bruising for no known reason
- Changes in bowel habits
- Blood in stools
Persistent cough or hoarseness
- Pain after eating, such as indigestion or heartburn
- Stomach pain
- Nausea and/or vomiting
- Trouble swallowing
- Changes in appetite
Severe and lasting fatigue
Fever or night sweats for no known reason
- A red or white patch in the mouth or on the tongue
- Numbness, bleeding or pain in the lips or mouth
- Headaches and/or migraines
- Changes in hearing and vision
- Drooping of the face
- Jaundice (yellowing of the skin and whites of eyes)
- Bodily sores that do not heal
- A change in existing bodily moles
- New moles appearing
- A flesh-coloured lump that turns scaly or bleeds
Swelling or lumps on the body such as the underarm, stomach, neck and groin.
Weight loss or gain for no known reason.
What causes Cancer?
Cancer is generally developed by accumulated damage to genes and/or exposure to cancer-causing substances. These substances are called carcinogens and may be a chemical substance, such as tobacco found in cigarettes, an environmental agent or a virus.
The causes of most cancers aren’t completely understood, although there are some risk factors that are recognized as placing people at a higher risk of developing cancer. These include:
- Smoking tobacco products
- Consumption of alcohol
- Genetic susceptibility and/or family history. Some genes that can predispose someone to cancer can be passed through family members.
- Diet, the consumption of specific foods, such as foods high in fat or highly-processed, may increase the risk of particular cancers
- Physical inactivity
- Being overweight or obese
- UV radiation
- Occupational exposure to agents, such as dust, chemicals or industrial processes
- Infections, for example, some types of human papillomavirus (HPV) can be linked to cervical and other cancers
There are also more particular risk factors for specific cancers.
Medicinal CBD for Cancer
A 2013 study published in the Journal of Pain and Symptom Management investigated the long-term safety and tolerability of THC/CBD spray and THC spray medications in relieving pain of cancer patients. The Δ9-tetrahydrocannabinol (THC)/cannabidiol (CBD) oromucosal spray, is a novel cannabinoid that was under investigation as an adjuvant therapy for this trial group.
The study consisted of 43 cancer patients with cancer-related pain who were previously not experiencing any pain relief whilst on chronic opioid medication, and had participated in a previous three-arm (THC/CBD spray, THC spray, or placebo), two-week parent randomised controlled trial (RCT), and took part in this open-label, multicenter, follow-up study.
Patients self-titrated either the THC/CBD spray or THC spray to the point at which their symptoms were relieved or maximum dose was reached, and were regularly checked for safety, tolerability, and evidence of clinical benefit of the treatment.
This clinical study found that participant pain was reduced from their baseline with each visit of the THC/CBD or THC spray participants. In a similar way, the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 participant scores demonstrated an improvement from the baseline in the domains of pain, fatigue and insomnia. There were no new safety concerns regarding extended THC/CBD use shown in this study.
The study illustrated the usefulness of THC/CBD and THC sprays as a long-term pain relief for cancer-related pain. It showed that it was well-tolerated throughout the subjects and the effectiveness of its pain relief didn’t wear off with long-term use. Patients that continued to use the study medication found that they did not need to increase the dosage amounts of it or other pain-relieving medication over time, which shows that the adjuvant use of cannabinoids in cancer-related pain could be beneficial over long periods of time.
Another 2011 study sought to see the efficacy of using cannabinoids to improve appetite, taste and smell perception and caloric intake in cancer patients.
The study was conducted on 21 adult advanced cancer patients that had poor appetites and chemosensory alterations and were randomised in a double-blinded manner to receive either THC or placebo capsules. They were required to take the medication twice a day for 18 days. Patients undertook a taste and smell survey, a 3-day food log, quality of life questionnaire, macronutrient and appetite preference assessments and an interview.
At the baseline level, the placebo and THC groups were comparable. Once the study was underway, the THC group recorded improved and enhanced sensory perception and stated that “food tasted better”. The proportion of calories consumed and premeal appetite also increased in the the THC group when compared to the placebo and also reported higher levels of relaxation and better quality of sleep. Quality of life scores and total caloric intake were improved in both groups.
It was concluded that cannabinoids may be useful in increasing the quality of life and enjoyment of food for cancer patients with chemosensory alterations. More in-depth research with a larger subject group would be needed in order to gain wider results.
Could CBD Cure Cancer?
There is yet to be substantial evidence finding whether CBD can directly cure cancer or not, but studies point to its effectiveness in easing cancer-related pain and symptoms in cancer patients. The long-term effectiveness of THC/CBD and THC spray medication in some people with cancer-related pain looks like a positive step in the direction of other CBD treatments, with participants indicating lower severity of pain throughout, and after, the duration of the study.
THC treatment may hold multiple clinical benefits for those who suffer sensory issues because of chemotherapy. Studies concluded that those who took a THC tablet had increased appetite and enjoyment of food compared to those who had taken a placebo. The benefits of THC for cancer patients outside its indication as a treatment for effects on appetite and nausea may be wide. Further research must be undertaken to further develop these theories.
New research and studies are constantly being conducted into the link between CBD and how it affects cancer patients, with hope on the horizon for new CBD-based cancer treatments and relief medication. An upcoming clinical trial run by the Centre for Medicinal Cannabis Research and Innovation in New South Wales is hoping to determine what dose and what frequency of medical cannabis is ideal to relieve key symptoms of those with advanced cancer.
Further research is needed to fully acknowledge the long-term effectiveness of using CBD as a treatment for all cancer types, and more data is required to find any cancer curing characteristics.