Colorectal cancer: From prevention to personalized medicine

Table 6 TNM classification of colorectal cancer

T = Primary tumor

TX = Primary tumor cannot be assessed

T0 = No evidence of primary tumor

Tis = Carcinoma in situ: intraepithelial or invasion of lamina propria

T1 = Tumor invades submucosa

T2 = Tumor invades muscularis propria

T3 = Tumor invades through the muscularis propia into subserosa or into nonperitonealized pericolic or perirectal tissues

T4a = Tumor penetrates to the surface of the visceral peritoneum

T4b = Tumor directly invades or is adherent to other organs or structures

N = Regional lymph nodes

NX = Regional lymph nodes cannot be assessed

N0 = No regional lymph node metastasis

N1a = Metastasis in one regional lymph node

N1b = Metastasis in two to three regional lymph nodes

N1c = Tumor deposit(s) in the subserosa, mesentery, or nonperitonealized pericolic or perirectal tissues without regional nodal metastasis

N2a = Metastasis in four to six regional lymph nodes

N2b = Metastasis in seven or more regional lymph nodes

M = Distant metastasis

MX = Distant metastasis cannot be assessed

M0 = No distant metastasis

M1a = Distant metastasis to one organ or site

M1b = Distant metastasis to more than one organ/site or the peritoneum

Staging

Stage I (T1-T2, N0, M0)

Stage IIA (T3, N0, M0)

Stage IIB (T4a, N0, M0)

Stage IIC (T4b, N0, M0)

Stage IIIA (T1-T2, N1, M0 and T1, N2a, M0)

Stage IIIB (T1-T2, N2b, M0; T2-T3, N2a, M0 and T3-T4a, N1, M0)

Stage IIIC (T3-T4a, N2b, M0 and T4b, N1-N2, M0 and T4a, N2a, M0)

Stage IVA (any T, any N and M1a)

Stage IVB (any T, any N and M1b)