**1. Introduction**

Colon cancer is a major cause of morbidity in the world and the second most common cause of cancer death. Most patients undergo curative resection of the primary colon cancer and removal of regional lymph nodes. Colon cancer mortality rates have improved over the years with the advancement of surgical techniques, diagnostic modalities and systemic therapy (**Figure 1**). Most important prognostic determinant is the stage of the cancer. The original pathological staging system used for colon cancer was the Dukes staging system which was based on the extent of penetration of the cancer through the bowel wall and whether there was involvement of regional lymph nodes (**Table 1**). It was originally described for rectal cancer but applied to colon cancer as well [2].

Staging of colon cancer has been further refined in detail and standardized according to the AJCC (American Joint Committee for Cancer)/UICC (Union for International Cancer Control) TNM staging system of which the latest version is the eighth edition which was adopted in 2018 [3]. The tumor and node definitions are shown in **Table 2**. Primary tumor and nodal factors define the stages as shown in **Table 3**.

The risk of recurrence increases with the stage, especially when there are nodal metastases. Postoperative adjuvant chemotherapy is utilized to eradicate the micrometastases which reduce the risk of recurrence and improve the cure rate. The role of adjuvant chemotherapy is well defined I stage III colon cancer; however, it

### **Figure 1.**

*Colon cancer related mortality from 1975 to 2010, (A) in males and (B) in females. Figures are from International Agency for Research on Cancer, global cancer observatory website [1].*


### **Table 1.**

*Dukes staging system for colorectal cancer.*


**163**

**Table 3.**

in resected colon cancer.

*Prognostic stage groups.*

**2. Primary treatment of colon cancer**

remains controversial in stage II. This chapter reviews the role of adjuvant therapies

About 70–80% of patients diagnosed with localized non-metastatic colorectal cancer undergo curative resection which is the main modality of treatment for those

*Adjuvant Therapies in Colon Cancer*

**M - Distant metastasis**

**Table 2.**

*DOI: http://dx.doi.org/10.5772/intechopen.93874*

N1a One regional lymph node is positive

• subserosa • mesentery

*The tumor, node, metastasis (TNM) staging system.*

N1b Two or three regional lymph nodes are positive

N2 Four or more regional lymph nodes are positive N2a Four to six regional lymph nodes are positive N2b Seven or more regional lymph nodes are positive

N1 One to three regional nodes are positive (tumor in lymph nodes measuring >0.2 mm), or

N1c No regional lymph nodes are positive, but there are tumor deposits in the

• or non-peritonised pericolic or perirectal/mesorectal tissues

Mo No distant metastasis by imaging, etc.; no evidence of tumor in distant sites or organs M1 Metastasis to one or more distant sites or organs or peritoneal metastasis is identified

**Stage T N M** 0 Tis N0 M0 I T1 N0 M0

IIA T3 N0 M0 IIB T4a N0 M0 IIC T4b N0 M0 IIIA T1-T2 N1/N1c M0

IIIB T3-T4a N1/N1c M0

IIIC T4a N2a M0

T2 N0 M0

T1 N2a M0

T2-T3 N2a M0 T1-T2 N2b M0

T3-T4a N2b M0 T4b N1-N2 M0

any number of tumor deposits are present and all identifiable lymph nodes are negative

### *Adjuvant Therapies in Colon Cancer DOI: http://dx.doi.org/10.5772/intechopen.93874*


### **Table 2.**

*Colorectal Cancer*

**162**

**T—Primary tumor**

*Dukes staging system for colorectal cancer.*

**Figure 1.**

**Table 1.**

**N - Regional lymph node**

TX Primary tumor cannot be assessed T0 No evidence of primary tumor

**Stage Description**

propria) T2 Tumor invades muscularis propria

structure

NX Regional lymph nodes cannot be assessed NO No regional lymph nodes metastases

through muscularis mucosae)

T4b Tumor directly invades or adheres to other organs or structures

Tis Carcinoma in situ: intramucosal (involvement of lamina propria with no extension

*Colon cancer related mortality from 1975 to 2010, (A) in males and (B) in females. Figures are from* 

Dukes B1 Tumor penetrates muscularis propria but not through bowel wall

Dukes C1 Tumor not through bowel wall with lymph node metastases Dukes C2 Tumor through bowel wall with lymph node metastases

*International Agency for Research on Cancer, global cancer observatory website [1].*

Dukes A Tumor confined to within submucosa

Dukes B2 Tumor penetrates through bowel wall

T1 Tumor invades submucosa (through muscularis mucosae but not into the muscularis

T3 Tumor invades through muscularis propria into pericolorectalic (subserosal) tissues T4 Tumor invades the visceral peritoneum or invades or adheres to adjacent organ or

T4a Tumor penetrates to the surface of the visceral peritoneum (including gross perforation of

the bowel through areas of inflammation to the surface of the visceral peritoneum)

*The tumor, node, metastasis (TNM) staging system.*


### **Table 3.**

*Prognostic stage groups.*

remains controversial in stage II. This chapter reviews the role of adjuvant therapies in resected colon cancer.
