A Trial of Tamoxifen and Letrozole in Recurrent and Persistent Squamous Cell Carcinoma of the Cervix

Although human papillomavirus (HPV) is a necessary cause of cervical cancer, HPV infection itself is inefficient and insufficient to cause cancer. New evidences have suggested endogenous and exogenous sex hormones confer risk of developing cervical cancer. In unscreened populations, incidence of cervical cancer starts after menarche and constantly increases before menopause, after then the incidence is flattening and declines \[21\]. Indeed, after menopause, newly incident CIN3 is seldom detected\[22\]. Large-scale epidemiological studies also showed high number of full-term pregnancy\[23\] (rather than abortion) and long-term use of hormonal contraceptives\[24\] to be independent risk factors of cervical cancer. These evidences pointed to female sex hormones to be another culprit of cervical cancer. The role of estrogen and ERα on HPV-induced cervical carcinogenesis is best demonstrated by the pK14-HPV E6/E7transgenic mice which, without estrogen exposure, develop benign skin tumors only. However, when these mice are treated with exogenous estradiol at physiological level, they develop cervical cancers in nearly 100% efficiency\[25-28\]. These cervical neoplasia recapitulate characteristics of human cervical cancer in all aspects: originated from the squamous-columnar junction, with early lesions of atypical squamous metaplasia, CIN and to invasive squamous cell carcinoma \[29\]. Most importantly, removal of exogenous estrogen or castration of these mice led to diminish of progression and partial regression of pre-existing neoplasia\[30\]. The investigators design an open, randomized, multi-center trial of tamoxifen and letrozole in treatment of recurrent or persistent squamous cell carcinoma of the cervix. Patients with recurrent or persistent SCC of cervix who are not amenable for further cytotoxic treatment will be randomized by block and by participating center to one of the two arms. The block size will be two . Medication will be given orally in daily dose of tamoxifen (Nolvadex) 20 mg, letrozole (Femara) 2.5 mg until disease progression or until the end of the study. Primary end point of the study is the response rate (complete response and partial response rates) for tamoxifen and letrozole arms. Secondary end points include progression-free survival (PFS) and overall survival (OS) compared to the historical results, ECOG Performance Status, quality of life and outcome predictors (biomarkers and clinical characteristics) of responsiveness and survival. The experienced survival data of the participating center will be compared.