Digestive 
Blood
Cardiovascular
Dermatology
Genitourinary,
Hormones
Infections
Oncology and
Musculo-skeletal
Mental health and
Parasites
Respiratory
Senses
Various
The system most commonly used for classification is the TNM. This acronym refers to three aspects of cancer: T refers to the size of it, N to the involvement of lymph nodes and M to whether other organs are involved or not.
According to these aspects, prostate cancer is grouped into the following steps or stages:
Stage I: The cancer is not evident or visible by diagnostic means. Diagnosis is accidental (when the patient sees the urologist for other reasons).
Stage II: An evident or visible tumour that does not go beyond the prostate. The tumour has not spread outside the prostate.
Stage III: The cancer goes beyond the capsule and affects tissues surrounding the prostate and seminal vesicles.
Stage IV: The cancer has spread to the lymph nodes or other parts of the body such as bones.
