Juan C Felix

University of Southern California, Los Ángeles, California, United States

Are you Juan C Felix?

Claim your profile

Publications (124)456.02 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Cervical cancer is the leading cause of cancer death among women in El Salvador. Utilizing data from the Cervical Cancer Prevention in El Salvador (CAPE) demonstration project, we assessed the health and economic impact of HPV-based screening and two different algorithms for the management of women who test HPV-positive, relative to existing Pap-based screening. We calibrated a mathematical model of cervical cancer to epidemiologic data from El Salvador and compared three screening algorithms for women aged 30 to 65 years: 1) HPV screening every 5 years followed by referral to colposcopy for HPV-positive women (Colposcopy Management [CM]); 2) HPV screening every 5 years followed by treatment with cryotherapy for eligible HPV-positive women (Screen and Treat [ST]); and 3) Pap screening every 2 years followed by referral to colposcopy for Pap-positive women (Pap). Potential harms and complications associated with overtreatment were not assessed. Under base case assumptions of 65% screening coverage, HPV-based screening was more effective than Pap, reducing cancer risk by approximately 60% (Pap: 50%). ST was the least costly strategy, and cost $2,040 per year of life saved. ST remained the most attractive strategy as visit compliance, costs, coverage, and test performance were varied. We conclude that a screen-and-treat algorithm within an HPV-based screening program is very cost-effective in El Salvador, with a cost-effectiveness ratio below per capita GDP. This article is protected by copyright. All rights reserved.
    International Journal of Cancer 01/2015; · 6.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the clinical and demographic characteristics that could influence regression of cervical intraepithelial neoplasia (CIN) from colposcopy to excision, and evaluated the association of the performance of multiple biopsies and endocervical curettage (ECC) with regression of high-grade (CIN 2+) by the time of excisional therapy.
    Journal of Lower Genital Tract Disease 08/2014; · 1.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective To determine the acceptability of self-collected versus provider-collected sampling among women participating in public sector HPV-based cervical cancer screening in El Salvador. Methods Two thousand women aged 30–49 years underwent self-collected and provider-collected sampling with careHPV between October 2012 and March 2013 (Qiagen, Gaithersburg, MD, USA). After sample collection, a random sample of women (n = 518) were asked about their experience. Participants were questioned regarding sampling method preference, previous cervical cancer screening, HPV and cervical cancer knowledge, HPV risk factors, and demographic information. Results All 518 women approached to participate in this questionnaire study agreed and were enrolled, 27.8% (142 of 511 responding) of whom had not received cervical cancer screening within the past 3 years and were considered under-screened. Overall, 38.8% (n = 201) preferred self-collection and 31.9% (n = 165) preferred provider collection. Self-collection preference was associated with prior tubal ligation, HPV knowledge, future self-sampling preference, and future home-screening preference (P < 0.05). Reasons for self-collection preference included privacy/embarrassment, ease, and less pain; reasons cited for provider-collection preference were result accuracy and provider knowledge/experience. Conclusion Self-sampling was found to be acceptable, therefore screening programs could consider offering this option either in the clinic or at home. Self-sampling at home may increase coverage in low-resource countries and reduce the burden that screening places upon clinical infrastructure.
    International Journal of Gynecology & Obstetrics 08/2014; · 1.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective: To compare the incidence of histopathological features in placentas from women with cholestasis of pregnancy to healthy individuals without ICP. Methods: Placentas from mothers with and without cholestasis of pregnancy were reviewed by a pathologist masked to the study group. Subjects were excluded if they had medical problems already associated with placental histopathology. Results: Twenty-four cases and 30 controls placentas were reviewed. Seventeen placental histopathological features were found. There was no statistically significant difference between the groups. Amongst patients with cholestasis, there was a decrease in villitis of unknown etiology in those treated with ursodeoxycholic acid. Conclusion: There is no difference in the placental histopathology in cholestasis of pregnancy compared to normal pregnancies, but treatment of patients with cholestasis of pregnancy with ursodeoxycholic acid may decrease findings of villitis of unknown etiology.
    Fetal and pediatric pathology 04/2014; · 0.40 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective. To determine the utility of random biopsy and endocervical curettage (ECC) during colposcopy among women who ultimately underwent cervical excisional biopsy. Materials and Methods. In a retrospective observational study, the charts were reviewed of every patient who underwent cervical excisional procedure performed be-tween June 2010 and August 2011, including the antecedent colposcopic examination and any pathological specimens. A random sample of 15% all pathologic specimens was re-viewed. Practice of biopsy, use of ECC, demographic factors, referral cytology results, lesion distribution, and size were assessed for correlation with high-grade cervical intra-epithelial neoplasia 2 or worse (CIN 2+). Results. A total of 555 patients were included in our analysis. Of them, 333 (60%) had CIN 2+ on colposcopy or excision. CIN 2+ was most likely in younger women and those referred for high-grade cytology. Among 111 women with no visual lesion seen at colposcopy, 66 underwent ECC alone, 33 had ECC and random biopsy, 9 were referred straight to excision, and 3 underwent random biopsy alone. Of the 99 who underwent ECC, this was consistent with the highest-grade lesion in 68% of cases. Among the 36 with random biopsy, this was con-sistent with the highest-grade lesion in 72% of cases. At the time of colposcopy, there were 326 who had CIN 2+ diagnosed with satisfactory colposcopy. Biopsy and ECC were performed in 278 cases. In 235 cases, biopsy alone showed CIN 2+; in 43, the biopsy and ECC both showed CIN 2+. In the remaining 48 cases, CIN 2+ was diagnosed with ECC alone. Conclusions. In those ultimately treated with excision, younger women and those whose referral cytology was high-grade both were at higher risk of high-grade histol-ogy. Random biopsy and ECC (even among satisfactory colposcopy) were significantly associated with disclosure of high-grade pathology.
    Journal of Lower Genital Tract Disease 01/2014; 18(2):xx-xx. · 1.11 Impact Factor
  • Nathan R Blue, Juan C Felix, Jenny Jaque
    [Show abstract] [Hide abstract]
    ABSTRACT: Primary ovarian leiomyoma is a rare benign ovarian tumor with only several reported cases in adolescents. Little is known about the origin or natural history of these rare tumors as they have occurred in a variety of presentations and were removed upon presentation without observation. A 14-year-old, premenarchal female was found to have a 4 cm mass which grew to 6.5 cm over two years. It appeared sonographically most consistent with a teratoma; however ,during surgical resection it was found to be solid, and on pathologic evaluation was identified as an ovarian leiomyoma. The growth of this patient's tumor with the onset of puberty supports hormonal responsivity, but its presence prior to menarche suggests an alternate origin, independent of gonadal hormones.
    Journal of pediatric and adolescent gynecology 12/2013; · 0.90 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To determine factors associated with the presence of residual disease in women who have undergone cervical conization for adenocarcinoma in situ (ACIS) of the cervix. We identified women who underwent a cervical conization for a diagnosis of ACIS followed by repeat conization or hysterectomy between January 1, 1995 and April 30, 2010. Data were summarized using standard descriptive statistics. 78 patients met study criteria. The presence of ACIS at the internal conization margin or in the postconization endocervical curettage (ECC) correlated with residual ACIS (p<0.001). A margin positive for ACIS was associated with residual glandular neoplasia in 68% of cases. An ECC positive for ACIS was associated with residual ACIS in 95% of cases. If both the margins and the ECC were positive for the presence of ACIS, 8% did not have residual disease, 77% had residual ACIS and 15% had invasive adenocarcinoma. If both the internal conization margin and the postconization ECC were negative for the presence of ACIS, 14% of the final specimens had residual ACIS and none had invasive cancer. The addition of postconization ECC to cone biopsy for ACIS of the cervix provides valuable prognostic information regarding the risk of residual ACIS. Women with ACIS who have both a negative postconization ECC and a negative conization margin have a 14% risk for residual ACIS and can be treated conservatively if desiring fertility. A positive postconization ECC or internal margin incurs significant risk of residual disease and 12-17% will have cancer.
    American journal of obstetrics and gynecology 12/2013; · 3.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We sought to test the diagnostic efficacy of a low-cost, liquid-based cervical cytology that could be implemented in low-resource settings. A prospective, split-sample Pap study was performed in 595 women attending a cervical cancer screening clinic in rural El Salvador. Collected cervical samples were used to make a conventional Pap (cell sample directly to glass slide), whereas residual material was used to make the liquid-based sample using the ClearPrep method. Selected samples were tested from the residual sample of the liquid-based collection for the presence of high-risk Human papillomaviruses. Of 595 patients, 570 were interpreted with the same diagnosis between the 2 methods (95.8% agreement). There were comparable numbers of unsatisfactory cases; however, ClearPrep significantly increased detection of low-grade squamous intraepithelial lesions and decreased the diagnoses of atypical squamous cells of undetermined significance. ClearPrep identified an equivalent number of high-grade squamous intraepithelial lesion cases as the conventional Pap. High-risk human papillomavirus was identified in all cases of high-grade squamous intraepithelial lesion, adenocarcinoma in situ, and cancer as well as in 78% of low-grade squamous intraepithelial lesions out of the residual fluid of the ClearPrep vials. The low-cost ClearPrep Pap test demonstrated equivalent detection of squamous intraepithelial lesions when compared with the conventional Pap smear and demonstrated the potential for ancillary molecular testing. The test seems a viable option for implementation in low-resource settings.
    Journal of Lower Genital Tract Disease 11/2013; · 1.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To determine the preoperative pelvic ultrasonographic characteristics of postmenopausal women diagnosed with endometrial cancer (EC) at our institution. Postmenopausal women with EC who underwent preoperative transvaginal pelvic ultrasound from 1999-2009 were identified from our institutional database. The histologic diagnosis was based on pathologic findings in the hysterectomy specimen. Endometrial echo complex (EEC) thickness was abstracted from ultrasound reports. In all instances, ultrasound preceded the biopsy by a maximum of 3 months. Means with standard deviations were calculated for all categorical data. Differences between type 1 and type 2 ECs were determined using Mann-Whitney U tests and Chi squared/ Fisher's exact tests, as appropriate. A p-value of < 0.05 was considered statistically significant. Among 250 patients with postmenopausal EC, 156 had type 1 EC while 94 had type 2 EC. Thirty-six percent of the cohort had an EEC ≤ 4 mm, including 37% of patients with type 1 EC and 34% of patients with type 2 EC (p = 0.63). There were no significant differences between type 1 and type 2 EC in any demographic characteristic, other than likelihood of postmenopausal bleeding. Current expert opinion recommends no further diagnostic procedure in a woman with postmenopausal bleeding and an EEC ≤ 4 mm. These results indicate that a sizable proportion of women with EC have EECs ≤ 4 mm during their initial evaluation. An EEC ≤ 4 mm does not completely rule out endometrial cancer and cannot supplant histologic evaluation.
    Gynecologic Oncology 07/2013; · 3.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: [This corrects the article on p. e62215 in vol. 8.].
    PLoS ONE 05/2013; 8(5). · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The molecular signals that control decisions regarding progenitor/stem cell proliferation versus differentiation are not fully understood. Differentiation of motile cilia from progenitor/stem cells may offer a simple tractable model to investigate this process. Wnt and Notch represent two key signaling pathways in progenitor/stem cell behavior in a number of tissues. Adenomatous Polyposis Coli, Apc is a negative regulator of the Wnt pathway and a well known multifunctional protein. Using the cre-LoxP system we inactivated the Apc locus via Foxj1-cre, which is expressed in cells committed to ciliated cell lineage. We then characterized the consequent phenotype in two select tissues that bear motile cilia, the lung and the testis. In the lung, Apc deletion induced β-catenin accumulation and Jag1 expression in ciliated cells and by lateral induction, triggered Notch signaling in adjacent Clara cells. In the bronchiolar epithelium, absence of Apc blocked the differentiation of a subpopulation of cells committed to the ciliogenesis program. In the human pulmonary adenocarcinoma cells, Apc over-expression inhibited Jag1 expression and promoted motile ciliogenic gene expression program including Foxj1, revealing the potential mechanism. In the testis, Apc inactivation induced β-catenin accumulation in the spermatogonia, but silenced Notch signaling and depleted spermatogonial stem cells, associated with reduced proliferation, resulting in male infertility. In sum, the present comparative analysis reveals the tissue-dependent consequences of Apc inactivation on proliferation and differentiation of ciliated cell progenitors by coordinating Wnt and Notch signaling.
    PLoS ONE 04/2013; 8(4):e62215. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVE: This study aims to determine whether long-term isoflavone soy protein (ISP) supplementation affects endometrial thickness and rates of endometrial hyperplasia and cancer in postmenopausal women. METHODS: In this randomized, double-blind, placebo-controlled trial, 350 postmenopausal women aged 45 to 92 years were randomized to a total daily dose of 154 mg of ISP or a milk protein-matched placebo for a 3-year period. Women with a surgically absent uterus were excluded from the analysis (final study population, N = 224). The main outcome measures were as follows: mean change in endometrial thickness on transvaginal ultrasound from baseline until up to 36 months of follow-up and the incidence of endometrial sampling, endometrial hyperplasia, and endometrial cancer. RESULTS: A total of 666 visits among 224 participants were evaluated. Treatment groups did not significantly differ on the mean baseline or on-trial changes in endometrial thickness. Of the 103 placebo-treated participants, 7 (6.8%) underwent endometrial biopsy; 6 (85.7%) of these biopsies were benign. One woman in the placebo group was diagnosed with complex endometrial hyperplasia with atypia and underwent hysterectomy. The pathology result from this surgical operation was stage IB endometrial cancer. Of the 121 participants in the soy group, 9 (7.4%) underwent endometrial biopsy. The results were benign in all nine cases (100%). Although the rate of hyperplasia/malignancy was higher in the placebo group (14.3% vs 0%), the difference was not statistically significant. CONCLUSIONS: Three-year ISP supplementation has no effect on endometrial thickness or on the rates of endometrial hyperplasia and cancer in postmenopausal women.
    Menopause (New York, N.Y.) 02/2013; · 3.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: The major contraceptive action of the levonorgestrel-releasing intrauterine system (LNG-IUS) is cervical mucus (CM) thickening, which prevents sperm penetration. No study to date has examined the temporal relationship between the insertion of the LNG-IUS and changes in CM quality and sperm penetration. STUDY DESIGN: Participants were enrolled in a clinically descriptive study to compare the quality of CM and three parameters of sperm penetration prior to insertion of the LNG-IUS and on Days 1, 3 and 5 after insertion. Measurements of estradiol, progesterone and levonorgestrel (LNG) in serum and LNG in CM were also carried out at these times. CM was analyzed using the World Health Organization CM grading criteria. Sperm penetration was determined using an in vitro sperm-CM penetration test. RESULTS: All 10 participants underwent LNG-IUS insertion during midcycle when CM quality was good and sperm penetration was excellent. On Day 1 after LNG-IUS insertion, the majority of participants demonstrated poor CM quality and poor sperm penetration. On Day 3, all participants had poor CM quality, and all but one subject had poor sperm penetration. By Day 5, all participants had poor CM quality and poor sperm penetration. LNG levels in CM peaked on the day after LNG-IUS insertion. CONCLUSION: Significant changes in quality of CM and sperm penetration were observed shortly after LNG-IUS insertion; however, CM can remain penetrable for up to 5 days when the LNG-IUS is inserted midcycle.
    Contraception 10/2012; · 3.09 Impact Factor
  • Gynecologic Oncology 11/2011; 123(2):429-430. · 3.69 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cancer-related coping strategies and social support, life stress, and optimism were tested in regression analyses as predictors of depression, affect, and quality of life among 54 low-income, immigrant Latina cervical cancer patients. Sixty-seven percent of the patients endorsed symptoms similar to diagnosable depression. Predictors significantly accounted for 35% to 54% of the variance in outcomes. Cancer-related coping strategies were found to mediate several of the relations between life stress, social support, and optimism and outcomes. Findings emphasize the need to consider the context within which patients live when assessing adjustment to cancer and developing culturally-sensitive interventions.
    Journal of Psychosocial Oncology 09/2011; 29(5):515-33. · 1.04 Impact Factor
  • American Thoracic Society 2011 International Conference, May 13-18, 2011 • Denver Colorado; 05/2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to compare the efficacy of the ultralow-dose estradiol vaginal ring with that of oral oxybutynin in the treatment of overactive bladder in postmenopausal women. Postmenopausal women with an overactive bladder were recruited from the general gynecology clinic. Participants were randomized to receive either the ultralow-dose estradiol vaginal ring or oral oxybutynin for 12 weeks. The primary outcome was a decrease in the number of voids in 24 hours. The secondary outcomes were quality-of-life questionnaires, vaginal pH levels, and vaginal maturation index. Fifty-nine women were enrolled. Thirty-one were randomized to receive oxybutynin, whereas 28 received the estradiol vaginal ring. Women who received oxybutynin had a mean decrease of 3.0 voids per day, and women who received the vaginal ring had a mean decrease of 4.5 voids per day, with no significant difference between the groups. There was a significant improvement in Urogenital Distress Inventory and Incontinence Impact Questionnaire scores in both groups, with no significant difference in improvement between the two groups. Ultralow-dose estradiol-releasing vaginal ring and oral oxybutynin seem to be similarly effective in decreasing the number of daily voids in postmenopausal women with overactive bladder.
    Menopause (New York, N.Y.) 04/2011; 18(9):962-6. · 3.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present study assessed the adequacy and predictive performance of visual inspection with acetic acid (VIA) in women over the age of 50 years and compared the specificity and sensitivity of VIA with that of the conventional cytology. In total, 588 Salvadoran women ages 50-79 underwent VIA, Pap smear, and cervical biopsy. VIA was considered adequate if the squamocolumnar junction was completely visible. A positive biopsy was defined as cervical intraepithelial neoplasia (CIN) 2 or worse. Age was negatively correlated with VIA adequacy (P=0.04). Nevertheless, the majority of women-even in the older age groups-had adequate examinations. The adequacy of VIA was positively correlated with gravida (P=0.01) and was higher in women who had been treated by cryotherapy (P=0.02). The rate of positive biopsies was unexpectedly low (n=6 [1%]) making it difficult to assess the predictive performance of VIA. In this small sample, the sensitivities of VIA (17%) and Pap (33%) were low; the high number of false negatives could not be fully explained by inadequacy of the examinations. Adequacy of VIA declined with age. However, the squamocolumnar junction was visible to the naked eye in the majority of women, indicating that they are good candidates for VIA.
    International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics 04/2011; 113(1):68-71. · 1.41 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In levonorgestrel intrauterine system (LNG-IUS) users, the prevention of sperm penetration through cervical mucus has not been demonstrated. Subjects were enrolled in an investigator-blinded study to compare quality and sperm penetrability of mid-cycle cervical mucus between LNG-IUS users and hormone-free controls. Cervical mucus was microscopically examined using World Health Organization (WHO) cervical mucus analysis (CMA). CMA score ≥10 of 15 points indicated cervical mucus favoring sperm penetration. Mucus was incubated with sperm using the WHO simplified slide test (SST) and Kremer sperm cervical mucus penetration test (SCMPT). Data from 14 LNG-IUS users and 16 controls showed 14% of LNG-IUS users had CMA score ≥10% vs. 69% of controls (p=.004). SST showed no sperm penetration for LNG-IUS users, significantly less than controls (0% vs. 64.3%, p<.001). SCMPT demonstrated no sperm mucus penetration for LNG-IUS users at 2 and 6 h (0% vs. 85% in controls with 2-h score ≥6, p<.001; 6 h 0% vs. 79% in controls, p<.001). Mid-cycle cervical mucus of LNG-IUS users is poor quality and prevents endocervical sperm transport in vitro.
    Contraception 12/2010; 82(6):491-6. · 3.09 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To compare visual inspection with acetic acid (VIA) with conventional cervical cytology as a follow-up cervical cancer screening method in women who had been treated previously with cryotherapy. Salvadoran women screened with VIA and treated with cryotherapy within 3 years were eligible to participate. Study participants were rescreened with VIA, Pap smear, colposcopy, 4-quandrant biopsy, and endocervical curettage. Of 147 women enrolled in the study, post-cryotherapy VIA was positive in 39 women (26.5%; 95% CI, 19.6%-34.4%). Of these 39, 1 woman had CIN 1 or higher on biopsy. Post-cryotherapy Pap smear was positive (ASCUS or higher) in 6 women (4.1%; 95% CI, 1.5%-8.7%). Of these 6, 2 women had CIN 1 or higher on biopsy. Post-cryotherapy specificity was significantly higher for Pap compared with VIA (95.8% [138/144]; 95% CI, 91.2%-98.5% vs 73.6% [106/144]; 95% CI, 65.6%-80.6%; P<0.001). As the single-visit approach for cervical cancer screening gains popularity, more women will have been treated with cryotherapy. Appropriate follow-up screening is therefore vital. Cytology may be a more suitable screening method than VIA in low-resource settings for women treated previously with cryotherapy.
    International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics 12/2010; 111(3):249-52. · 1.41 Impact Factor

Publication Stats

2k Citations
456.02 Total Impact Points


  • 1995–2014
    • University of Southern California
      • • Department of Obstetrics and Gynecology
      • • Keck School of Medicine
      • • Department of Medicine
      • • Norris Comprehensive Cancer Center
      • • Department of Pathology
      Los Ángeles, California, United States
  • 1997–2013
    • University of California, Los Angeles
      • Department of Obstetrics and Gynecology
      Los Angeles, California, United States
  • 1999–2012
    • Keck School of Medicine USC
      Los Ángeles, California, United States
  • 2010
    • Bellevue University
      Белвю, Nebraska, United States
    • NYU Langone Medical Center
      • Department of Obstetrics and Gynecology
      New York City, NY, United States
    • Kaiser Permanente
      • Department of Obstetrics and Gynecology
      Oakland, CA, United States
  • 2005
    • Advocate Good Samaritan Hospital
      Chicago, Illinois, United States
  • 2001
    • Children's Hospital Los Angeles
      Los Angeles, California, United States