I Overview
In recent years, with the continuous improvement of people’s living standard, changes in dietary habits and diet structure as well as the aging of population, the incidence and mortality rate of colorectal cancer in China have been on the rise.
Diagnostic techniques and applications
(A) Clinical manifestations.
Early stage rectal cancer may have no obvious symptoms, and the following symptoms may appear only when the disease has progressed to a certain extent: 1.
(1) Change of defecation habit. Zheng Naiguo, Department of General Surgery, Guiyang Second Affiliated Hospital of Traditional Chinese Medicine
2. change of stool characteristics (thinning, bloody stool, mucus stool, etc.).
3. abdominal pain or abdominal discomfort.
4. Abdominal mass.
5. Intestinal obstruction.
6. anemia, wasting, weakness, low fever, etc.
(B) physical examination.
1. General condition, superficial lymph nodes of the body.
2, abdominal visual examination and palpation, check the presence of intestinal pattern, intestinal peristaltic wave, abdominal masses.
3. Rectal finger examination: all suspected rectal cancer patients must routinely undergo anorectal finger examination. To understand the size, texture, circumference of the intestinal wall, activity, distance from the anal verge, infiltration of the tumor to the outside of the intestine, and relationship with surrounding organs, etc. Touch gently, do not squeeze, and observe whether the finger stains with blood.
(iii) Laboratory examination.
1.Blood routine: to understand whether there is anemia.
2. Urine routine: observe whether there is hematuria, combine with urinary tract imaging to understand whether the tumor invades the urinary system.
3. Stool routine: the presence of red blood cells and pus cells should be noted.
(4) Stool occult blood test: It is important for the diagnosis of small amount of bleeding in the gastrointestinal tract.
(iv) Endoscopic examination.
Proctoscopy and sigmoidoscopy are suitable for rectal lesions with low lesion location.
All patients with suspected rectal cancer should have fiberoptic colonoscopy or e-colonoscopy, except for the following cases.
1. poor general condition that makes it difficult to tolerate.
2. acute peritonitis, intestinal perforation, extensive intra-abdominal adhesions, and complete intestinal obstruction
3. perianal or severe intestinal infections, radiation enteritis.
4. women during pregnancy and menstruation.
Before the endoscopy, preparations must be made, such as eating a liquid diet, taking laxatives, or cleaning and washing the intestine to clean the feces.
Because the intestinal canal can be crinkled during the examination, the lesion seen by endoscopy can be inaccurate from the anus, so it should be combined with CT or barium enema to clarify the location of the lesion.
(E) Imaging examination.
1. Barium enema examination, especially air-barium double imaging, is an important means to diagnose rectal cancer. However, caution should be exercised if intestinal obstruction is suspected.
2. B-type ultrasound: ultrasound examination can understand whether there is recurrence of metastasis and has the superiority of convenience and speed.
CT examination: The purpose of CT examination is to clarify the depth of lesion invasion to the intestinal wall, the extent of extra-mural spread and the site of distant metastasis.
(1) providing the staging of colorectal malignant tumors.
(2) To detect recurrent tumors.
(3) To evaluate the response of the tumor to treatment.
(4) To elucidate the internal structure and clarify the nature of intra- and extra-pressure lesions in the intestinal wall found by barium enema or endoscopy
(5) Evaluation of intra-abdominal masses found by barium examination and clarification of the origin of the masses and their relationship to the surrounding organs.
MRI examination: The indications for MRI examination are the same as those for CT, and MRI examination is preferred in the following cases: (1) preoperative staging of rectal cancer; (2) evaluation of liver metastases from rectal cancer; (3) suspicion of peritoneal and subperitoneal liver lesions.
5. Transrectal endoluminal ultrasound: endoluminal ultrasound or endoscopic ultrasound of the rectum is recommended as a routine examination for the diagnosis and staging of middle and low rectal cancer.
6.PET-CT: not routinely used, but can be an effective adjuvant examination for metastatic recurrent lesions that cannot be clarified by conventional examination.
7. Excretory urography: it is not used as a routine preoperative examination, but only for those whose tumor may invade the urinary tract.
(F) Serum tumor markers.
CEA and CA19-9 must be detected for rectal cancer patients before diagnosis, treatment, evaluation of efficacy and follow-up; CA242 and CA72-4 are recommended; AFP is detected for those with liver metastasis; CA125 is detected for those with ovarian metastasis.
(vii) Pathological histological examination.
Pathological biopsy to clarify the nature of lesion is the basis of rectal cancer treatment. Those biopsy diagnosed as invasive cancer should undergo standardized rectal cancer treatment. If the depth of infiltration cannot be determined by pathology due to biopsy sampling restrictions and the diagnosis of high-grade intraepithelial neoplasia, clinicians should integrate other clinical conditions to determine the treatment plan. When it is determined to be recurrent or metastatic rectal cancer, the K-ras gene status of tumor tissue is detected.
(viii) Open abdominal exploration.
In the following cases, the abdomen should be opened for investigation.
(1) The diagnosis is still not clear by various means and rectal tumor is highly suspected.
2) Intestinal obstruction and conservative treatment is ineffective.
3. suspected intestinal perforation.
4. Gastrointestinal hemorrhage which is ineffective by conservative treatment.
(ix) Differential diagnosis of rectal cancer.
1. Rectal cancer should be differentiated from the following diseases.
(1) Hemorrhoids Hemorrhoids and rectal cancer are not difficult to distinguish, and misdiagnosis is often due to lack of careful examination. Hemorrhoids are mostly painless blood in stool, and the blood is bright red and does not mix with stool, while rectal cancer blood in stool is often accompanied by mucus and appears as mucus blood stool and rectal irritation symptoms.
(2) Anal fistula. Anal fistula is often caused by paranal abscesses formed by anal sinusitis. Patients with a history of paranal abscess, local redness and pain, and rectal cancer have more obvious differences in symptoms, so it is easier to differentiate.
(3) Amoebic enteritis. The symptoms are abdominal pain and diarrhea, and the lesion involving the rectum may be accompanied by shortness of breath. The stool is dark red or purplish blood and mucus. Enteritis can cause the proliferation of granulation and fibrous tissue, thickening the intestinal wall and narrowing the intestinal lumen, which can be easily misdiagnosed as rectal cancer, and fiberoptic colonoscopy and biopsy are effective means of differentiation.
(4) Rectal polyps. The main symptom is blood in the stool, fiberoptic colonoscopy and biopsy are effective means of differentiation.
Pathological assessment
(a) Pathological types.
1. Early rectal cancer.
The cancer cells are limited to the submucosal layer of the colorectum, called early colorectal cancer (pT1), and the WHO classification of gastrointestinal tumors also calls the lesions with infiltration in the mucosal layer “high-grade intraepithelial neoplasia”.
2. The general types of progressive colorectal cancer.
(1) Bulging type. Any tumor body protruding into the intestinal lumen belongs to this type.
(2) Ulcerated type. Any tumor that forms an ulcer deep to or through the muscle layer is of this type.
(3) Infiltrative type. The tumor infiltrates diffusely into all layers of the intestinal wall, causing local thickening of the intestinal wall, but there is often no obvious ulcer or bulge on the surface.
3. Histological types.
(1) Adenocarcinoma: (1) papillary adenocarcinoma; (2) tubular adenocarcinoma; (3) mucinous adenocarcinoma; (4) indolent cell carcinoma.
(2) Undifferentiated carcinoma.
(3) Adenosquamous carcinoma.
(4) squamous cell carcinoma
(5) small cell carcinoma
(6) Carcinoid tumor. 4.
4. Relationship between grading and histological type.
The relationship between cell grading and histological type of colorectal cancer is shown in Table 1.
Table 1 Relationship between grading and histological type
Grading Histological type
WHO four-grade classification
Low grade
Grade Ⅰ
Grade II Highly differentiated (tubular) adenocarcinoma, papillary
Intermediate differentiated (tubular) adenocarcinoma
High grade
Grade III
Grade Ⅳ Hypodifferentiated (tubular) adenocarcinoma, mucinous adenocarcinoma, indolent cell carcinoma, undifferentiated carcinoma, medullary carcinoma
TNM stage of rectal cancer
American Joint Committee on Cancer (AJCC)/International Union Against Cancer (UICC) TNM staging system for colorectal cancer (7th edition, 2010)
Primary tumor (T)
Tx Primary tumor cannot be evaluated
T0 No evidence of primary tumor
Tis Carcinoma in situ: confined to the intraepithelium or invading the lamina propria of the mucosa
T1 Tumor invades the submucosal layer
T2 Tumor invades the lamina propria
T3 Tumor penetrates the lamina propria to reach the subplasma layer, or invades the rectum without peritoneal coverage
T4a Tumor penetrates the peritoneal layer
T4a Tumor penetrates into the visceral layer of the peritoneum
T4b Tumor directly invades or adheres to other organs or structures
Regional lymph nodes (N)
Nx Regional lymph nodes cannot be evaluated
N0 No regional lymph node metastasis
N1 1-3 regional lymph node metastases
N1a 1 regional lymph node metastasis
N1b With 2-3 regional lymph node metastases
N1c Tumor implantation (TD, tumor deposit) in subplasma, mesenteric, peri-peritoneal colon/rectal tissue without peritoneal coverage, without regional lymph node metastasis
N2 More than 4 regional lymph node metastases
N2a 4-6 regional lymph node metastases
N2b 7 or more regional lymph node metastases
Distant metastasis (M)
M0 No distant metastasis
M1 with distant metastases
M1a Distant metastases confined to a single organ or site (e.g. liver, lung, ovary, non-regional lymph nodes)
M1b Distant metastases distributed to more than one organ/site or peritoneal metastases
Anatomic staging/prognostic group
Stage T N M Dukes MAC
0 Tis N0 M0 – –
I T1 N0 M0 A A
T2 N0 M0 A B1
IIA T3 N0 M0 B B2
ⅡB T4a N0 M0 B B2
IIC T4b N0 M0 B B3
ⅢA T1-2 N1/N1c M0 C C1
t1 n2a m0 c c1
IIIB T3-4a N1/N1c M0 C C2
T2-3 N2a M0 C C1/C2
t1-2 n2b m0 c c1
IIIC T4a N2a M0 C C2
t3-4a n2b m0 c c2
T4b N1-2 M0 C C3
ⅣA Any T Any N M1a – –
ⅣB Any T Any N M1b – –
Note: 1. cTNM is clinical staging and pTNM is pathological staging; the prefix y is used for tumor staging after receiving neoadjuvant (preoperative) therapy (e.g., ypTNM), and patients in complete pathological remission are staged as ypT0N0cM0, which may be similar to stage 0 or 1. The prefix r is used for patients who relapse after a period of tumor-free interval obtained with treatment (rTNM).
Dukes stage B includes both patients with a better prognosis (T3N0M0) and a worse prognosis (T4N0M0), as does Dukes stage C (any TN1M0 and any TN2M0). mac is a modified Astler-Coller stage.
2. Tis includes tumor cells confined to the basement membrane of the gland (intraepithelial) or the lamina propria (intramucosa) of the mucosa, without crossing the mucosal muscle layer to reach the submucosa.
3. Direct invasion of T4 includes penetrating the plasma membrane and invading other intestinal segments, which is confirmed by microscopic diagnosis (e.g. cecum cancer invading the sigmoid colon), or tumors located in the retroperitoneum or subperitoneal intestinal canal, which directly invade other organs or structures after penetrating the intrinsic base of the intestinal wall, such as tumors in the posterior wall of the descending colon invading the left kidney or lateral abdominal wall, or rectal cancer of the middle and lower segments invading the prostate, seminal vesicle gland, cervix or vagina.
4. cT4b if the tumor is visually adherent to other organs or structures, but pT3 if no tumor is present at the site of the adhesion microscopically. v and L sub-stages are used to indicate the presence of vascular and lymphovascular infiltration, while PN is used to indicate nerve infiltration (which can be site-specific) [to be continued (II)