Biological parameters and prognosis
In addition to prognostic indicators such as pathology and staging, there are many prognostic factors such as biological indicators, molecules and genes associated with colorectal cancer. Although these parameters can help to improve the prognosis estimation, further studies are needed to confirm whether they have independent prognostic value.
(i) Routine serological indicators
1. Biochemical indicators
There is no consensus on the association between laboratory findings and prognosis. Most studies have concluded that hemoglobin, hematocrit, white blood cell count, liver function indicators (such as GGTP, SGOT, SGPT, LDH, etc.), total serum protein, and ferritin are not associated with prognosis. However, Hannisdal et al. found a poorer prognosis and shorter survival time when hematocrit exceeded 30 mm/h and leukocyte count exceeded 10 × 109/L (P < 0.05). Xu Fangying reported [90] that urine glucose had independent significance on prognosis, while blood glucose had no significance.
2.Serum carcinoembryonic antigen
Serum carcinoembryonic antigen (CEA) has the ability to cause immune evasion of tumor cells and contribute to the spread and metastasis of tumor cells. Although CEA is not suitable for the early diagnosis of colorectal cancer, a large amount of clinical data proves that the elevated serum CEA value of colorectal cancer patients before surgery indicates a wide range of lesions and a poor prognosis after surgery. Some studies have suggested that CEA can be used as a negative prognostic factor independent of TNM staging [93]. The American Cancer Consortium (AJCC) has even suggested modifying TNM staging to I-IV CxC0C1 based on preoperative serum CEA levels, classifying preoperative serum CEA levels as a class I prognostic factor [94].
However, it is controversial whether there is a correlation between serum CEA values and prognosis. Indeed, in clinical practice, more than half of the patients, even in advanced stages, did not observe elevated serum CEA levels. In 2002, 245 patients with colorectal cancer in Zhongshan University Cancer Hospital had positive serum CEA with greater than normal reference value (≥5ng/ml), accounting for 42.0%. Except for these patients, the blood CEA level would not be able to objectively reflect the tumor load in vivo, and whether there is a difference in survival rate between these patients with high and non-high CEA remains to be further followed up.
Combined testing of CEA and other tumor markers has also been reported more frequently. It is generally believed that the determination of CEA, CA19-9 and CA-50 has some significance for the prognosis. However, the sensitivity of single test is not high, and the combined test has diagnostic value.
In recent years, humoral and cellular immunity against CEA has become a hot spot in colorectal cancer research. Foreign studies on anti-CEA antibodies concluded that most colorectal cancer patients have serum presence of anti-CEA antibodies with high specificity and concentration.Albanopoulos et al. considered anti-CEA antibodies as a statistically significant prognostic factor. Wu Xiaojun et al [95] tested anti-CEA antibodies in 69 colorectal cancer patients and the positive rate was 63.8% (44/69); combined testing of CEA and anti-CEA antibodies increased the positive rate to 84.1%, and the correlation with prognosis is being studied in follow-up.
3.CA19-9
CA19-9 is a glycoantigen, a salivary acidified lactic acid-Ne lactopentose associated with Lewis blood group substances, which binds to endothelial cell surface receptors and functions in relation to cancer cell infiltration and metastasis, and is released into the bloodstream in tumor patients. Most studies [96, 97] have concluded that CA19-9 is less sensitive than CEA, but it is more specific for diagnosing disease recurrence. One study found CA19-9 expression in 71.0% of primary tumors and a positive rate of CA19-9 in preoperative serum (>37UI/ml) of 20.6%, while the rate of CA19-9 positivity in serum 1 month after surgery was only 6.6%. Positive CA19-9 in the primary tumor, preoperative and postoperative serum predicted increased mortality. Those who were negative for all 3 indicators had no recurrence and a 5-year survival rate of 97.1%. In contrast, 62.5% of those with all 3 positive indicators had recurrence, and the 5-year survival rate was only 42.8%.
(B) Nuclear DNA content of cancer cells
The prognosis of patients can be determined by detecting the ploidy of tumor cell DNA. In colorectal cancer patients, there is an increase in diploid loss as the cells progress from precancerous to malignant. The increase in CEA levels in aneuploid tumor tissue is significant compared to diploid tumors. Aneuploidy usually increases with increasing stage, and aneuploid tumors have a more unfavorable and higher growth rate than diploid tumors. Aneuploid tumors are usually associated with other pathological factors suggestive of poor prognosis [98-100].
However, the value of cell nuclear DNA content in determining the prognosis of colorectal cancer is still debated. It has been suggested that colorectal cancer cell nuclear DNA ploidy system is the most meaningful predictor of recurrence and prognosis. although Bauer et al. did not confirm the relationship between colorectal cancer cell nuclear DNA content and prognosis, they found that the prognosis was poor when the percentage of S-phase cells exceeded 20% in Dukes A and B phase cell nuclear division proliferation cycle.
Witzig reported [99] that DNA sequence provides the most useful prognostic information than DNA ploidy.DNA sequence can be a determinant of high risk in lymph node-negative patients.
(iii) Oncogenes and oncogenes
1. Oncogenes
After Pulciani discovered in 1982 that activated cellular oncogenes could transform NIH3T3 murine cells, the relationship between colorectal cancer genes and their biological behavior was also explored at the molecular level. The existence of mutations and amplification of genes in colorectal cancer cells has been confirmed, such as mutation of codon 12Ki-ras in the nucleus and amplification of c-Ki-ras, c-Ha-ras, N-ras, c-Myc, c-fos and other genes. However, the relationship between genes and prognosis is not clear.
(1) ras
The ras oncogene family includes H-ras, K-ras and N-ras, and its mutations are an important genetic alteration in colorectal cancer. The majority of mutations occur in the K-ras gene, while N-ras mutations are rare and H-ras mutations are almost absent. ras mutations have variable prognostic significance. mutations in ras codon 12 or 13 were found to be associated with prognosis in four groups of 498 patients. Elnatan et al. reported more aggressive tumors and poorer prognosis in the left hemicolectomy if present, but not in the right hemicolectomy. ras mutations were more significant in patients with Dukes C stage, according to Andreyev et al. Another study of seven groups of 610 patients found no association between ras mutations and prognosis. There is no essential difference in experimental design and patient selection between the two main types of studies mentioned above. A closer analysis suggests that those reporting no prognostic significance were mostly limited to a particular stage of tumor. In contrast, those reporting significance were mostly mixed cases from Dukes A/D. It may be that colorectal cancers with ras mutations have a strong ability to infiltrate independent of Dukes staging [101-103].
(2) c-Myc
Alterations in the c-Myc oncogene include overexpression and gene amplification. More than half of colorectal cancers have overexpression of Myc genes ranging from 3 to 40-fold. A few tumors had 3- to 4-fold amplification of the Myc gene. Gene overexpression did not correlate with amplification. Most tumors had only overexpression without gene amplification. Approximately 30% of patients have low levels of c-Myc amplification, the extent of which correlates with chemotherapy sensitivity. rNA analysis Most studies concluded that c-Myc gene copy number or RNA expression is not associated with prognosis. However, patients with c-Myc overexpression have been reported to have a better prognosis than patients without overexpression, and this effect is limited to patients with pre-existing mutations in p53 of the tumor. c-Myc protein immunohistochemical studies have also been reported by several groups (Miller et al., 1992, 118 cases; Bhatavdekar et al., 1997, 48 cases) The prognostic significance of positive c-Myc protein staining is not significant [ 103-105].
(3) TGFa and TGFβ
TGFa has been shown to promote colon cancer cell growth in vitro by acting with EGFR to cause cell proliferation. younes et al [106] studied 105 patients and suggested that patients with low expression of TGFa (<25% positive cells) have a worse prognosis than those with high expression (>25% positive cells). tGFβ inhibits epithelial growth and promotes differentiation, and stimulates mesenchymal cell proliferation and cell migration. Matsushita et al. demonstrated that TGFβ mRNA and protein expression was significantly higher in tumors than in normal colonic mucosa, suggesting that tumor mesenchymal vascular endothelial cells and fibroblast-like cells have the ability to bind TGFβ secreted by colorectal cancer cells. tGFβ indirectly promotes tumor growth through paracrine effects of mesenchymal components. promote tumor growth. Pan Yuanqing et al [107] concluded that TGFβ1 has the greatest prognostic risk.
(4) c-erbB-2
c-erbB-2, also known as Her-2/neu, is a glycoprotein with tyrosine kinase activity with a molecular weight of 185 kD. Kapitanovic et al [108] (1997) studied 151 cases of colorectal adenocarcinoma and c-erbB-2 was expressed in all cases in this group, with 43% of strong positivity, and its immunohistochemical staining was negatively correlated with survival, with moderate intensity The mean survival of positive staining cases was 120 weeks, only 28 weeks for strong positives and 275 weeks for weak positives. koy et al. studied 164 cases of Dukes stage B colorectal cancer, 33.5% of the tumors stained positive for cytoplasm and the 5-year survival rate was 47% in the positive group compared to 77% in the negative group, and Kapitanovic both concluded that the prognosis of high c-erbB-2 expression was poor [108, 109 ]. In contrast to the above-mentioned 3 groups of reports, heteroploid colorectal cancer has been reported to have a good prognosis if c-erbB-2 is overexpressed. Therefore, the relationship between c-erbB-2 expression and prognosis of colorectal cancer should also be studied in depth based on the organization of large cases and strict control of comparative conditions in order to draw reliable conclusions [110].
(5) Bcl-2
Bcl-2 is an oncogene that has a role in encoding a 25 kD protein that inhibits apoptosis. Many studies in colorectal cancer have shown no relationship between Bcl-2 overexpression and recurrence or survival, and no difference in response to 5-FU treatment between patients with Bcl-2-positive and negative tumors. Some studies suggest that Bcl-2-positive patients have a better prognosis. The prognosis of bcl-2-positive/p53-negative tumors has also been reported to be better than that of other staining types [111].
2. oncogenes
(1) p53
p53 is a very important oncogene, and about 50% of cancers have mutations in the p53 gene. Mutation is the most important form of loss of functional activity of P53. The literature reports that more than 75% of colorectal cancers have loss of chromosome 17p, indicating that p53 alteration has an important role. p53 is involved in the malignant process of colorectal adenoma turning into cancer, and in colorectal cancer associated with ulcerative colitis, p53 alteration plays a role in its early stage.
The relationship between p53 alterations and the prognosis of colorectal cancer has been published in many papers, but there are many types of monoclonal antibodies used for detection, and the positivity criteria vary from 1% nuclear positivity to more than 10% nuclear positivity as p53 positivity criteria. Second, the localization of positivity is also controversial. Some studies have reported that the prognostic significance of p53 cytoplasmic positivity is greater than that of nuclear positivity (Sun et al., 1992; Bosari et al., 1994). However, it is unclear whether this cytoplasmic staining is a methodological artifact or a true result with biological significance. Positive p53 reactions in the cytoplasm are sometimes difficult to evaluate correctly. However, in general mutations in p53 are correlated with prognosis [112].
(2) DCC
Smad 4, Smad 2 and DCC are three colorectal cancer-related genes located on the long arm of chromosome 18, and in recent years it has been found that colorectal carcinogenesis is associated with loss of heterozygosity (LOH) at 18q. Vogeistoin et al. found that 70% of colorectal cancers and 50% of late adenomas have loss of 18q. DCC (deleted in colon cancer) is one of the first anti-cancer genes localized at 18q21. 2. DCC (deleted in colon cancer) was one of the first anti-oncogenes localized at 18q21. 2. The protein encoded by DCC functions similarly to a family of adhesion molecules and its altered expression is associated with prognosis in colorectal cancer patients [103, 113].Jen et al. and Qgunbiyi et al [114] reported that loss of the 18q allele was associated with prognosis in stage II colorectal cancer and that stage II patients with loss of 18q were similar to stage III patients.
Shibata et al. studied DCC expression by immunohistochemistry using polyclonal antibody (721), microwave antigen repair method. The 5-year survival rate of stage II patients with positive DCC staining was 94.3%, while only 61.6% of those with negative staining. The 5-year survival rate of DCC positive cases in stage III patients was 59.3% and 33.2% in negative cases.
(3) Rb-1
The Rb gene is located on chromosome 13q14 and has at least 12 exons constituting the gene encoding a protein of 928 amino acids with a molecular weight of 105 kD (p105-Rb), a class of DNA-binding proteins that regulate the transcription of certain genes controlling proliferation and inhibit cell growth. gope et al. found that 70% of colorectal cancers had 2-5 times more Rb gene amplification than normal mucosa. The remaining tumors were similar to, but not lower than, normal. Studies with Southern blot showed that Rb gene was not lost or transcriptionally inactivated in colorectal cancer. Karyotype studies have shown that 48% to 55% of colorectal cancers have non-random acquisition of chromosome 13 (triploidy or tetraploidy). In colorectal cancer Rb gene expression is increased, and how exactly that Rb gene functions remains an unsolved mystery [1].
(4) p27
The p27 gene is an important cell cycle inhibitor that acts in the G1 phase of the cell cycle and prevents the G0/S phase transition in the cell cycle. p27 is also an anti-oncogene and is localized at 12p13. It has been shown that the level of p27 gene expression in the nucleus is negatively correlated with tumor malignancy and therefore may be a new tumor marker and prognostic indicator [115]. applied microwave repair immunohistochemistry to analyze 149 cases of colorectal cancer, and staining positivity was localized in the nucleus, cytoplasm, or nucleus and plasma; the mean survival of p27-positive tumors (n=134) was 151 months, while negative cases (n=15) were only 69 months.
(5) p21
The relative molecular weight of the protein encoded by the p21 gene is about 21 kD. p21 protein binds to various cyclin-CDK complexes, inhibits CDK kinase activity, prevents cells from passing the G1-S phase barrier, keeps cells in G1 phase, inhibits cell proliferation, or gives cells with damaged DNA a chance to repair in order to maintain genomic stability and prevent malignant transformation of cells.
Immunohistochemical studies of a total of 399 patients yielded 54% p21 positive tumors, with positivity rates ranging from 31% to 71%, which is related to the monoclonal antibodies used and the varying criteria for determining positivity. Three of these groups reported p21-positive tumors with a poor prognosis, and only one group reported that p21-positive staining was considered an independent prognostic factor [111].
Fu et al [116] used immunohistochemistry to detect p53 and p21/WAFl in pre-radiation biopsy specimens of primary rectal cancer and observed the relationship between p53 and p21 expression and post-radiation histopathological changes as well as clinical features. Results Most p53+ or p21- tumors were resistant to radiation, while most p53- or p21+ tumors were sensitive to radiation. The decrease in volume of p53- or p21+ tumors after radiation was more pronounced than that of p53+ or p21- tumors. p53+ or p21- patients were more prone to recurrence and distant metastases and had lower 5-year survival rates than P53- or P21+ patients, and although there was no statistical difference, detection of p53 and p21 expression may be a useful parameter for selecting preoperative radiotherapy in radiosensitive patients.
(6) p16
p16 is a cyclin-dependent kinase (CDK) inhibitor that blocks pRb protein phosphorylation and blocks the cell cycle in G1 phase. p16 is one of the key molecules in the Rb cell cycle control pathway (p16-Rb-p21ras), which is down-regulated in most human tumor cells. The mechanisms of its deregulation are mostly gene deletion, mutation, promoter methylation, and binding of its products by oncogene proteins and post-transcriptional modifications. It has been reported that the frequency of p16 deletion in colorectal cancer ranges from 50% to 67%, and its expression deficiency is not significantly correlated with age and significantly correlated with survival, with a poor prognosis for p16-negative colorectal cancer [117-119].
3.Combined detection
The process of tumorigenesis requires multiple genes and multi-step alterations to induce or maintain its malignant state, and the simple application of one or several oncogenes and oncogenes as prognostic indicators may be too simplistic, and comprehensive analysis of the expression and mutation of various oncogenes and oncogenes will further elucidate their biological behavior and their relationship with clinical prognosis, which still requires further in-depth studies.