International Journal of Radiation Oncology*Biology*Physics
Clinical InvestigationThe Significance of Tumoral ERCC1 Status in Patients With Locally Advanced Cervical Cancer Treated With Chemoradiation Therapy: A Multicenter Clinicopathologic Analysis
Introduction
Cervical cancer is a global health concern, and remains the third most common cancer in women worldwide (1). It has been more than a decade since landmark clinical trials proved that the addition of concomitant chemotherapy to radiation therapy (RT) regimens improves both progression-free and overall survival (OS) (2). These trials also found increased acute toxicity in patients treated with concomitant chemoradiation therapy (CRT) as compared with those treated with RT alone. Further advances in cervical cancer treatment in recent years include the evolution of intensity modulated RT and image guided brachytherapy, and the development of 3-dimensional image-based treatment planning guidelines 3, 4, 5. Despite these treatment advances, there is still a subset of patients who are not cured of their disease. This may be due to underlying chemo- and/or radioresistance in their tumors. There are currently no routinely used predictive tumor markers of CRT responsiveness in cervical cancer patients. This would be clinically valuable because predictive markers could allow the identification of patients who might have tumors resistant to standard CRT.
Excision repair cross-complementation group 1 (ERCC1) is a protein that plays a role in several DNA repair pathways. In nucleotide excision repair, the ERCC1-XPF complex plays a critical role in the removal of DNA intrastrand crosslinks (6). The ERCC1-XPF endonuclease has also been implicated in homologous recombination and in the repair of DNA double-strand breaks via a Ku-independent end-joining pathway 7, 8.
High ERCC1 expression has been shown to be associated with poor treatment response and survival in multiple tumor sites, including head-and-neck and esophageal cancer patients treated with RT and platinum-based chemotherapy 9, 10, 11, 12. However, the predictive value of ERCC1 expression has not been well studied in patients with locally advanced cervical cancer treated with CRT. There is some evidence that human cervical tumor cells with high ERCC1 mRNA are resistant to platinum-based chemotherapy (13). In addition, there are recent clinical data on the impact of ERCC1 status on response to neoadjuvant cisplatin chemotherapy in patients with cervical cancer (n=43), with low ERCC1 an independent factor for response to chemotherapy (14). Another small study (n=50) reports association of lack of ERCC1 expression with better clinical outcomes, in patients with International Federation of Gynecology and Obstetrics (FIGO) stage II or III cervical cancer treated with CRT (15). The relationship between high ERCC1 expression and cisplatin resistance can be attributed to enhanced removal of platinum-induced DNA adducts by the nucleotide excision repair pathway.
We have shown that low ERCC1 mRNA and protein expression were associated with worse survival in cervical cancer patients treated with radiation alone (16). RT kills tumor cells by inducing DNA damage, the most lethal of which is double-strand breaks. Given the role of ERCC1 in the repair of DNA damage, it is possible that its expression level may be associated with RT response.
In the present study, we evaluated the association of ERCC1 protein expression, using the FL297 rabbit polyclonal antibody, in pretreatment tumor samples of cervical cancer patients treated with radical CRT from 3 major Canadian cancer centers. We previously reported that ERCC1 FL297 expression was correlated with ERCC1 mRNA expression, unlike ERCC1 8F1 expression, which was not correlated with ERCC1 mRNA expression (16). Others have also deemed ERCC1 FL297 to be a more specific and appropriate reagent for ERCC1 detection in formalin-fixed paraffin embedded tissue 17, 18. Here we report the results of the largest study evaluating the significance of tumoral ERCC1 protein expression with clinical outcome in locally advanced cervical cancer patients treated with radical CRT.
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Patients, treatment, and biosamples
Two hundred sixty-four patients with cervical cancer who completed definitive CRT between 1999 and 2004 at 3 major Canadian cancer centers (Center 1, n=74; Center 2, n=124; Center 3, n=66) were identified from retrospective and prospective databases. None of the patients were treated with primary surgery or RT alone. Patients were excluded if they had prior definitive treatment for cervical cancer or active malignancy at another site. A chart review was performed, and clinical, treatment, and
Results
The baseline clinical and tumor characteristics are shown in Table 1. The median follow-up of patients was 4.5 years (range 0.32-9.2 years). The 5-year PFS was 56%, and OS was 66%. There was no difference in PFS or OS among the 3 centers (P=.90, P=.87, respectively). There was no difference in PFS (P=.54) or OS P=.64) based on whether the patients received carbogen as part of their treatment.
The staining pattern for FL297 was predominantly nuclear with a fainter cytosolic signal, similar to
Discussion
In this study, we found that high ERCC1 protein expression measured using the FL297 antibody and AQUA quantitative immunohistochemistry, is associated with worse survival on univariate analysis in cervical cancer patients treated with CRT. This is the largest study evaluating the association of ERCC1 expression with outcome in cervical cancer patients. These results are consistent with studies evaluating ERCC1 expression and response to cisplatin chemotherapy in other tumor sites. Our previous
Acknowledgments
The authors acknowledge the contribution of Ms. Mie Konno (Calgary) for data collection and specimen coordination and Judy Quintos (Toronto) for study coordination. We also thank Dr Rob Bristow, Dr David Gaffney, and Dr Adam Dicker for their advice and support in advancing this multicenter Canadian research project.
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Cited by (0)
Supported by the RTOG Translational Research Program U10CA21661, RTOG U10 CA21661, and CCOP U10 CA37422 NCI grants, The Terry Fox Foundation, the Alberta Cancer Foundation, and the Southern Alberta Cancer Research Institute.
Conflict of interest: A.F. has financial activities with Vertex Pharmaceutical.
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Co-senior authors.