8 questions about cancer answered

Cancer can be complicated and confusing to understand. If you or a loved one have been diagnosed with cancer, you may find that learning more about it can help ease some of your worries and prepare you for treatment or next steps. Even if you haven’t been personally affected by cancer, having knowledge about it can help you to support a loved one through their cancer journey and better understand what they’re going through.

Keep reading to learn more about cancer and find answers to some commonly asked questions. 

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1. What is cancer?


Cancer isn’t one disease. There are more than 100 types of cancer, but they all have one thing in common – they start in our cells. Our bodies are made up of trillions of cells that normally grow and divide as needed. When cells are abnormal or get old, they usually die. Cancer starts when something goes wrong in this process and some of the body’s cells grow and divide out of control.

2. What causes cancer?

This is one of the questions we’re asked the most. But the truth is, very few cancers have a single known cause. Most cancers seem to be caused by a complex mix of many risk factors, but sometimes cancer develops in people who don’t have any risk factors.

A risk factor is any substance or condition that increases the risk of developing cancer. Cancer risk factors may play different roles in starting cancer and helping it grow. There are risks that we can’t change like getting older, having certain genetic changes and family history. There are other risks that are influenced by behaviour as well as where we live, work and play including: 

  • smoking tobacco  
  • not protecting yourself from the sun
  • having excess body weight
  • not having a healthy diet
  • not getting enough physical activity
  • drinking alcohol
  • coming into contact with harmful chemicals at home or at work
  • having certain types of infections

The good news is, there's a lot you can do to reduce your risk of cancer – starting with living a healthy, active lifestyle. You can take small but important steps to stay on the path of great health no matter your age. Making change to reduce your cancer risk doesn’t mean you won’t get cancer. It means that your change getting cancer is lower.

3. How does cancer grow and spread?

Our bodies are made up of trillions of cells grouped together to form tissues and organs. Genes inside each cell tell it when to grow, work, divide and die. Normally, our cells follow these instructions and we stay healthy. But sometimes the instructions get mixed up, causing our cells to grow and divide out of control. Over time, the abnormal cells may form a lump in the body called a tumour.

Not all tumours are cancer. Non-cancerous (benign) tumours have cells that stay in one place and don’t spread. These tumours don’t usually come back after they are removed. Cancerous (malignant) tumours can grow into nearby tissues and spread to other parts of the body.

Cancer cells have the same needs as normal cells – they need a blood supply to bring oxygen and nutrients to grow and survive. When a tumour is very small, it gets oxygen and nutrients from nearby blood vessels. As a tumour grows, the cancer cells send signals for the tumour to make new blood vessels. This brings more oxygen and nutrients to the tumour, causing it to keep growing. It also allows cancer cells to get into the blood and spread more easily to other parts of the body.

As a tumour gets bigger, cancer cells can spread to nearby tissues and structures by pushing on normal tissue beside the tumour. Cancer cells also make enzymes that break down normal cells and tissues as they grow. Cancer that grows into nearby tissue is called local invasion or invasive cancer. Cancer can also spread, or metastasize, from where it first started when the cells break away from the tumour and travel to a new location in the body through the blood or lymphatic system. 

4. What do cancer grade and stage mean?

Cancer grade is based on how the cancer cells look. Knowing the cancer grade helps doctors predict how fast the cancer will grow and how likely it is to spread. Grade is usually described using a number from 1 to 3 or 4. The higher the number, the more different the cancer cells look from healthy cells and the faster they are growing.

Cancer stage lets doctors know how much cancer is in a person’s body, where it is and how far it has spread. This helps them know which treatments to use. Cancer can spread within the organ that it started in, to nearby lymph nodes or to distant sites. Stage is described using a number from 1 to 4. Stage 1 cancer is usually small and hasn’t spread outside of where it started. The higher the number, the larger the tumour or the more it has spread. Stage 4 usually means it has spread to distant sites.

5. What are the symptoms of cancer?

Signs and symptoms caused by cancer will vary depending on what part of the body is affected. Some early warning signs of cancer are:

  • a new or unusual growth, lump or swelling anywhere on your body 
  • a sore that does not heal
  • a change in the shape, size or colour of a mole or wart
  • blood in your pee (urine), poop (stool) or phlegm
  • any unusual bleeding or discharge from your nipple or vagina
  • any change in bladder habits, such as finding it hard to pee (urinate) or pain when you pee
  • any change in bowel habits, such as going poo more often with looser poop (diarrhea) or finding it hard to poo (constipation), that lasts more than a few weeks a nagging cough, hoarseness or a croaky voice
  • indigestion or problems swallowing
  • weight loss, fever, tiredness, aches or pains that you can’t explain 

A change to your body might be nothing, but it could be something more serious. If you have health concerns that could be a sign or symptom of cancer or another serious illness, report them to your doctor right away.

6. How does cancer treatment work?

There are several types of treatment for cancer. The main cancer treatments are surgerychemotherapy and radiation therapy. Other treatments include hormone therapytargeted therapyimmunotherapy and stem cell transplant.

The type of treatment a person will have can depend on many factors, including the type of cancer and the stage, the person’s age and their personal preferences. Sometimes people who have the same cancer will be given different treatments. Some people will have only 1 treatment, but most people will have a combination of treatments such as surgery with chemotherapy or radiation therapy or both.

7. Can vaccines help prevent cancer?

Most vaccines help protect us from infections, such as measles or polio. They are made from weakened or killed germs that do not cause the infection, but instead stimulate the immune system to make antibodies against the germs. A person will then be protected from getting the infection if they come in contact with it.

Cancer treatment vaccines are different because they try to get the immune system to attack cancer cells that are already in the body. Most cancer treatment vaccines are still being studied in clinical trials. But we do have some vaccines that prevent viral infections that cause cancer or contribute to cancer development.Preventative vaccines stimulate the immune system to attack certain viruses before they cause an infection. These vaccines are given to healthy people before cancer develops. Currently, there are two types of preventative vaccines approved in Canada: 

  • Human papillomavirus (HPV) vaccines protect against infection caused by certain types of HPV. Most people who are sexually active will have an HPV infection at some point in their life. While most infections go away on their own, high-risk HPV infections can lead to cervical, anal, vaginal, vulvar, penile, mouth and throat cancers.  
  • Hepatitis B vaccines may lower the risk of developing liver cancer in some people. Hepatitis is inflammation of the liver that can be caused by certain viruses. People with long-term infection with the hepatitis B virus are at a higher risk of liver cancer.

Learn more about vaccines and speak to your doctor about whether getting vaccinated is right for you. 

8. Is cancer research making a difference?

Cancer is a complex disease. With over 100 different types, cancers vary in how they grow, spread and respond to treatment – which is why there isn’t a single cure. However, over the last several decades, research advances have helped us better understand cancer, detect it earlier, diagnose it more accurately and improve treatment so that people faced with cancer not only survive, but thrive long after.

Today, about 64% of Canadians diagnosed with cancer will survive at least 5 years after their diagnosis. This is up from 55% in the early 1990s. In the 1940s, survival was about 25%. For some cancers, like thyroid and testicular, the survival rates are more than 90%. We are also close to turning some cancers into manageable diseases, making cancer something you live with, not die from.

While cancer researchers across the country are working hard to save lives and help more Canadians live better with and beyond cancer, it’s important to remember that it can take years – or even decades – for research breakthroughs to be implemented. But with the help of our supporters, donors, partners, staff and volunteers, we’re accelerating this progress – and continuing to make a difference in the lives of Canadians every day. 

If you have more questions about cancer, we’re here to help. You can turn to us for trusted information or reach out to one of our trained Cancer Information Helpline specialists at 1-888-939-3333, via email or through live chat right here on our website. Our free publications are available to download and give you reliable and up-to-date information that's easy to understand.

If you or a loved one is living with cancer, our support programs and services can help answer your questions about cancer, manage life with cancer, find community and connection, and build wellness and resilience.