“Cancer” and “tumor” are two different terms that are often used interchangeably. However, these terms should be kept distinct and should not be mixed, because they represent two different health conditions.
Cancer vs. Tumor
Both cancer and tumor are defined as abnormal cell growth. However, they are not the same. There are subtle yet significant differences among these terms. Here is the definition of these terms (see below Source no. 1).
- Tumor: A tumor, which is also called a lump, is an abnormal mass that develops due to unnatural and uncontrolled cell growth. It can grow anywhere in the body. Depending on the tumor’s behavior (whether the cells spread or not), it can be benign or cancerous/malignant.
- Cancer: Cancer is a malignant tumor in which the rapidly dividing cells start to infiltrate the surrounding tissues and spread to other body parts (metastasis). In simple words, cancers represent a more violent form of tumors.
Benign vs. Malignant (Cancerous) Tumors
Benign tumors are well-demarcated tumors. These tumors remain within their confines and do not involve the surrounding structures. In fact, most benign tumors are surrounded by a membrane-like structure, called a capsule, which separates them from the adjacent normal tissues.
By comparison, cancers are poorly demarcated tumors. The word “cancer” is of Latin origin meaning “crab”. It was given this name because cancer cells infiltrate into the surrounding tissues, where they “grab the cells and do not let go”- just like a crab. Surgeons cannot tell just by looking where cancer ends and normal tissues begin.
Metastasis represents the spread of a tumor from its primary site (the site of its origin) to a distant site. For example, breast cancer may spread to the bones.
Benign tumors cannot spread to other body sites. Metastasis does not occur in benign tumors.
Cancers, on the other hand, spread to other body parts. Some cancerous tumors spread more rapidly than others. Breast cancer, for instance, can quickly metastasize to the liver, lungs, and bones (Source no. 4).
Both benign and malignant tumors can come back at any time. The pattern of recurrence varies greatly between different types of tumors. In general, malignant tumors recur faster than benign tumors (see below Source no. 7).
However, this pattern cannot be generalized for all tumors. Some benign tumors, like some breast tumors, recur faster than malignant tumors (Sources no. 5 & 6).
Most benign tumors remain silent and go unnoticed for a long time. In fact, most of the benign tumors are identified incidentally upon a medical checkup.
But benign tumors do produce some local signs due to the increasing pressure of their growing size at the site of their origin. This may cause pain at that site or tissue death (necrosis) (Source no. 8).
The symptoms of malignant tumors are widespread. In addition to the local symptoms, malignant tumors produce a lot of other apparently vague symptoms in the body. Including fever, weight loss, malaise, poor wound healing, changes in bowel habits and so on (read more about cancer here).
The prognosis of benign tumors is very good. Once removed, they do not come back.
The prognosis of malignant tumors depends on a lot of variables. The prognosis becomes excellent if the cancer is detected early, and treatment starts in time. Late detection and delay in treatment make the prognosis poor.
Not all tumors are cancerous. It’s important that you know the difference between a benign and malignant tumor because while similar at first sight, both tumors have different symptoms, prognosis and treatment options.
Any abnormal lump in the body should be enough to raise a suspicion in you, and you should consult your doctor without any delay.
Sources & References:
- John Hopkins Medicine, 2012.
- American brain tumors association, 2014.
- Canadian Cancer Society, 2015.
- National Cancer Institute, 2013.
- American Journal of roentology, 1990.
- Massachusetts General Hospital, 2015.
- Breastcancer.org, 2012.
- Surgical Oncology: An Algorithmic Approach, 2011.
- US Library of medicine, 2015.
- Current Neurology and Neuroscience Reports, 2008.
- Familydoctors.org, 2014.
- Journal of Alternative and Complementary medicine, 2012.