What is cancer?

Organ systems

Immune system

The immune system defends the body against infection and disease. It is made up of cells and organs that work together to protect the body.

Lymphatic system

The lymphatic system is part of the immune system. It includes the tonsils, spleen, thymus, lymph nodes and lymph vessels.

Blood and bone marrow

The blood is made up of blood cells in a liquid called plasma. Blood cells are made in the bone marrow, the soft spongy area inside most bones.

Endocrine system and hormones

The endocrine system is a group of glands and cells in the body that make hormones and release them into the blood.

Female sex organs and reproductive system

The female sex organs and reproductive system include the vagina, vulva, cervix, uterus, ovaries and fallopian tubes.

Male sex organs and reproductive system

The male sex organs and reproductive system include the penis, urethra, prostate, seminal vesicle, scrotum and testicles.

Your trusted source for accurate cancer information

With just $5 from readers like you, we can continue to provide the highest quality cancer information for over 100 types of cancer.

We’re here to ensure easy access to accurate cancer information for you and the millions of people who visit this website every year. But we can’t do it alone.

If everyone reading this gave just $5, we could achieve our goal this month to fund reliable cancer information, compassionate support services and the most promising research. Please give today because every contribution counts. Thank you.