What are the stages of Cancer?
Kidlin's Law states, "If you can write down the problem clearly, you are halfway to solving it"." This principle holds in oncology, as the correct identification of Cancer and its stage is utterly important because the treatment options vary significantly for different Cancer stages.
Cancer staging is a way of describing how spread the Cancer is in the body from its origin. Typically, there are four stages of Cancer; however, 5th stage 0 is sometimes used to describe specific abnormal cell growth. [1] Unfortunately, the higher stages of Cancer are usually associated with worse prognosis, with the most significant decrease in survival chances seen between stages 3 and 4. [2]
Stage 0 Cancer is usually used to describe abnormal growth of the cells in a body that can potentially become Cancerous. However, there are not enough abnormal cells to form a tumour yet. [1] Stage 0 Cancers are usually treated with surgery, sometimes with radiotherapy, but chemotherapy is not administered. For example, stage 0 breast Cancer, lumpectomy (the removal of abnormal cells and a small amount of surrounding tissue) or mastectomy (removing all or part of the breast) are the most common treatments that help prevent the Cancer from growing further. [3]
Stage 1 Cancer is considered an early stage Cancer, as it is small and localised to one area. It has not spread to any lymph nodes or other organs. Just like stage 0, it is not treated with chemotherapy but rather with surgery and radiotherapy. [4] Stage 1 Cancers are usually associated with great survival rates, which are higher for any other stage of that Cancer; for example, for breast Cancer, stage 1 survival rates are almost 100%, meaning most women who are diagnosed with stage 1 breast Cancer survive. [5] However, some Cancers might be more dangerous, and stage 1 lung Cancer has around 65% survival 5-year survival rates, meaning only 65% of people diagnosed with lung Cancer will survive more than 5 years after diagnosis. [6] In many Cancers, stage 1 also has two substages, 1A and 1B, which depend on the size of the tumour, with stage 1A being used to describe smaller tumours, which did not spread to lymph nodes and are associated with slightly better prognosis, compared to stage 1B. [7]
Stage 2 Cancer is also considered an early stage Cancer and is referred to as tumours that are still localised but that have grown more deeply into the nearby tissue (and are bigger than stage 1 tumours) and could have spread to the nearby lymph nodes. It is more serious and advanced than stage 1, and so is associated with a worse prognosis than stage 1 Cancer. [8] Patients diagnosed with stage 2 lung Cancer have a 40% 5-year survival rate, compared to the previously mentioned 65% for patients diagnosed with stage 1. [6] Stage 2 Cancers are usually treated with surgery or radiotherapy. [8]. There are three substages for some of the stage 2 Cancers: 2A, 2B and 2C. As with stage 1 Cancers, stage 2A Cancers have a better prognosis than stage 2B or 2C. These substages also depend on the size of the tumour and how much it has spread in the nearby lymph nodes. [9]
Stage 3 Cancer is considered a locally advanced Cancer. It is more advanced than stage 2 and has spread to the nearby lymph nodes. It is more extensive and could have also spread to the nearby tissue. Stage 3 Cancers have significantly lower survival rates than stage 2.[10] For instance, patients diagnosed with stage 3 lung cancer have only 15% 5-year survival rates. [6] At this stage, chemotherapy is used, along with surgery and radiotherapy, as the benefits that chemotherapy can deliver outweigh the toxicities it can yield. Again, just as for other stages, stage 3 is divided into 3A, 3B and 3C, based on how far the Cancer has spread into the surrounding tissue, its size, and whether there are multiple tumours. [10]
Stage 4 Cancer, also called metastatic Cancer, is the final stage of Cancer and so is the most dangerous one. In stage 4, the Cancer spreads from where it originated to the other parts of the body during a process called metastasis. The metastasis can happen through Cancer cells moving through the lymphatic system or blood vessels to parts of the body and stopping there, forming new tumours. [11] The prognosis for stage 4 Cancers is very low. Patients diagnosed with stage 4 lung Cancer have a 5% 5-year survival rate. [6] Different Cancers tend to metastasise to specific organs, such as bladder Cancer, which tends to metastasise into bones and lungs. However, the reasons behind this phenomenon. Are yet to be discovered. [11] The reasons behind the incurability of metastatic Cancer lie in the fact that the Cancers that metastasise usually have enough correct genetic mutations to be resistant to many treatments. Additionally, every metastatic tumour in every organ might have a different microenvironment, and so require different therapy. At the moment, metastatic Cancers are treatable but largely incurable. [12]
This numerical grading system does not fully cover how the Cancer is staged and simplified. The TNM staging is usually used in clinics to stage Cancer. T stands for the size of the original tumour, N for whether the Cancer has spread to lymph nodes and M for whether the Cancer has undergone metastasis and spread to other parts of the body. T goes from 1 to 4, where T1 is a small tumour, and T4 is large; N goes from 0 to 3, N0 meaning Cancer did not spread to the lymph nodes, N3 meaning lots of lymph nodes contain Cancer. Finally, M is either 0, with no metastasis, or 1, with metastasis. So, stage 2B Cancer can be T2 N1 M0, while stage 4 is likely T4 N3 M1. [1]
This is how the Cancer stage is determined. As previously said, early identification is the key to high survival chances, so there is no reason to avoid medical examinations with doctors. In the end, the life is at stake.
References
Cancer research UK (2017). Stages of cancer. [online] Cancer Research UK. Available at: https://www.cancerresearchuk.org/about-cancer/what-is-cancer/stages-of-cancer.
McPhail, S., Johnson, S., Greenberg, D., Peake, M. and Rous, B. (2015). Stage at diagnosis and early mortality from cancer in England. British Journal of Cancer, [online] 112(S1), pp.S108–S115. doi:https://doi.org/10.1038/bjc.2015.49.
team, N. (2023). Stage 0 Breast Cancer - Symptoms, Treatment & Survival Rate. [online] National Breast Cancer Foundation. Available at: https://www.nationalbreastcancer.org/breast-cancer-stage-0/https://www.nationalbreastcancer.org/breast-cancer-stage-0/ [Accessed 19 Jan. 2025].
City of Hope (2019). What is Stage 1 Cancer & How is Stage 1 Cancer Treated? [online] Cancer Treatment Centers of America. Available at: https://www.cancercenter.com/stage-one-cancer.
Cancer Research UK (2020). Survival for breast cancer | Breast Cancer | Cancer Research UK. [online] www.cancerresearchuk.org. Available at: https://www.cancerresearchuk.org/about-cancer/breast-cancer/survival.
Cancer Research UK (2017). Survival | Lung cancer | Cancer Research UK. [online] Cancerresearchuk.org. Available at: https://www.cancerresearchuk.org/about-cancer/lung-cancer/survival.
Liu, D. (2020). Cancer Staging. [online] Cancer Treatment Centers of America. Available at: https://www.cancercenter.com/cancer-types/breast-cancer/stages.
Cancer Treatment Centers of America. (2019). What is Stage 2 Cancer & How is Stage 2 Cancer Treated? [online] Available at: https://www.cancercenter.com/stage-two-cancer.
National Breast Cancer Foundation. (n.d.). Stage 2 (II) And Stage 2A (IIA) Breast Cancer Overview. [online] Available at: https://www.nationalbreastcancer.org/breast-cancer-stage-2/.
Cancer Treatment Centers of America. (2019). What is Stage 3 Cancer & How is Stage 3 Cancer Treated? [online] Available at: https://www.cancercenter.com/stage-three-cancer.
National Cancer Institute (2020). Metastatic Cancer: When Cancer Spreads. [online] National Cancer Institute. Available at: https://www.cancer.gov/types/metastatic-cancer.
www.cancer.gov. (2017). Overcoming the Challenges of Metastatic Cancer - National Cancer Institute. [online] Available at: https://www.cancer.gov/news-events/cancer-currents-blog/2017/metastatic-cancer-kaplan.
