The role of p53 as a surrogate marker for chemotherapeutical responsiveness in ovarian cancer

BRCA2 N372H Polymorphism and Risk of Epithelial Ovarian Cancer: An Updated Meta-Analysis With 2344 Cases and 9672 Controls

The BRCA2 N372H is the only common polymorphism that leads to the amino acid change based on the reports up to date. Previous studies explored the relationship between the single nucleotide polymorphism and ovarian cancer risk, but the results were inconsistent or inconclusive.To investigate the association between N372H in BRCA2 gene and ovarian cancer susceptibility, a systematic literature search was performed for related publications in the databases of PubMed, Gene, and Google Scholar.Total 2344 cases and 9672 controls in eligible studies were included in this meta-analysis. χ -based Q test and an I index were used to identify the heterogeneous records. Potential publication biases were assessed by Begg and Egger tests.In the overall analysis, the results showed a significant association between BRCA2 codon 372 polymorphism and increased risk of ovarian cancer (HH versus NN: odds ratio (OR) = 1.22, 95% confidence interval (CI) 1.01-1.48, P = 0.037). In the Australia subgroup analysis, significant association was also detected (HH versus NN: OR = 1.40, 95% CI 1.04-1.87, P = 0.026). The subgroup analysis for serous cancer subgroup showed that the significant association could be detected under recessive model (OR = 1.38, 95% CI, 1.01-1.89, P = 0.04) and under homozygote comparison (OR = 1.46, 95% CI, 1.06-2.01, P = 0.022).Our meta-analysis suggests that the N372H polymorphism is associated with susceptibility of ovarian cancer. The allele H might increase the risk of ovarian cancer, especially, for ovarian cancers of the serous subtype.

Mutant p53 and the response to chemotherapy and radiation

In addition to playing roles in the genesis and progression of cancer, mutant p53 also appears to play a significant role in the response to cancer therapy. In response to chemotherapy and radiation, two mainstays of cancer treatment, most cancer cells harboring p53 mutations show a reduced sensitivity compared to cells lacking p53 or those with wild type p53. However, there are also many instances where mutant p53 has shown no effect or enhances cellular sensitivity to chemotherapy and radiation. Similar to the in vitro cellular studies, the majority of clinical studies show a correlation between the presence of mutant p53 in patient tumors and adverse outcomes following treatment with chemotherapy agents or radiation in comparison to tumors with wild-type p53. However, it still remains unclear whether the presence of mutant p53 in tumors can serve as a reliable prognostic factor and aid in treatment planning. Thus, as genomic analysis of patient tumors becomes more cost effective, the role of mutant p53 in tumor responses from cancer therapy ultimately needs to be addressed. This chapter will discuss current mechanisms of how p53 mutations affect cellular responses to chemotherapy and radiation and discuss patient outcomes based on p53 status.

p53-autoantibody may be more sensitive than CA-125 in monitoring microscopic and macroscopic residual disease after primary therapy for epithelial ovarian cancer

PURPOSE

To evaluate the use of p53-autoantibodies (p53-aab) for monitoring minimal disease after standard therapy of advanced epithelial ovarian cancer (EOC).

METHODS

Retrospective analysis of p53-aab in preoperative and long-term follow-up serum samples from 10 patients selected for representing three relevant EOC subgroups: platinum-sensitive disease after macroscopic complete debulking (n = 4) and platinum-sensitive (n = 3) or platinum-resistant disease (n = 3), both after suboptimal debulking with residual tumor of <1 cm diameter. p53-aab levels were quantified by a sandwich ELISA in two independent experiments. CA-125 values of all samples and clinical information were retrieved from medical records.

RESULTS

Patients with early relapse (median PFS 7 months, n = 8) had high p53-aab levels throughout follow-up while CA-125 values had dropped below the cut-off after primary surgery during or after chemotherapy in these cases. Patients with seroconversion to p53-aab negativity experienced prolonged PFS (n = 2; #1: 50 months, #2: no evidence of disease for 36 months until last follow-up). Continued p53-aab positivity was not related to the resection status or platinum sensitivity.

CONCLUSIONS

p53-autoantibodies may be a highly sensitive marker for minimal residual tumor mass after surgery and/or chemotherapy rather than standard CA-125, possibly due to the different nature of these markers. CA-125 released by cancer cells is related to tumor mass, whereas p53-aab levels can indicate the presence of few tumor cells due to amplification by the immune system. Seroconversion of p53-aab could be associated with long-term survival.

Potential markers for detection and monitoring of ovarian cancer

This paper reviews current screening techniques as well as novel biomarkers and their potential role in early detection of ovarian cancer. Ovarian cancer is one of the most common reproductive cancers and has the highest mortality rate amongst gynecologic cancers. Because most ovarian cancer diagnoses occur in the late stages of the disease, five-year survival rates fall below 20%. To improve survival rates and to lower mortality rates for ovarian cancer, improved detection at early stages of the disease is needed. Current screening approaches include tumor markers, ultrasound, or a combination. Efforts are underway to discover new biomarkers of ovarian cancer in order to surmount the obstacles in early-stage diagnosis. Among serum protein markers, HE4 and mesothelin can augment CA125 detection providing higher sensitivity and specificity due to the presence of these proteins in early-stage ovarian cancer. Detection testing that includes methylation of the MCJ gene and increased expression of vascular endothelial growth factor is correlated to poor prognosis and may predict patient survival outcome. Detection testing of biomarkers with long-term stability and combination panels of markers, will likely lead to effective screening strategies with high specificity and sensitivity for early detection of ovarian cancer.