Comparison of depth of necrosis achieved by CO2- and N2O-cryotherapy

Locoregional Thermal and Chemical Tumor Ablation: Review of Clinical Applications and Potential Opportunities for Use in Low- and Middle-Income Countries

This review highlights opportunities to develop accessible ablative therapies to reduce the cancer burden in LMICs.

Pilot Study on the Effect of a Single Topical Application of Trichloroacetic Acid 85% on Normal Cervical Tissue

Background: Early detection and treatment of cervical intraepithelial neoplasia (CIN) through a “see and treat” approach is a pillar of cervical cancer prevention programs in developing countries such as Indonesia. One of the major challenges faced is the limited N2O or CO2 gas supply for cryotherapy. Thus, an alternative therapeutic method such as trichloroacetic acid (TCA) topical application is needed as an alternative solution. The effectiveness of this therapy will depend on its destructive effect on eliminating the whole lesion in CIN.

Objective: To estimate the extent of damage in the normal cervical tissue after a single topical application of 85% TCA solution.

Design and Methods: This research was an intervention study carried out by applying ±5 ml of 85% TCA solution into the cervix of 40 patients scheduled for total hysterectomy for indications other than cervical pathology 24 h before surgery. The extent of tissue destruction was determined microscopically using histopathological specimens. The study protocol is registered at www.clinicaltrial.gov (ID NCT04911075).

Results: In the final analysis, 39 subjects were included. The necrotic area was detected at the superficial layer, accompanied by the full epithelial erosion thickness. In addition, there were also fibrotic areas resembling burned tissue in the stroma. The mean depth of destruction was 1.16 ± 0.01 mm in the anterior lip and 1.01 ± 0.06 mm in the posterior lip. There was no significant depth difference between the anterior and posterior lips (p ≥0.05). Moreover, the 85% TCA topical application was tolerable, as represented by the fact that the vast majority (82.1%) of participants experienced pain with a visual analog scale score of <4.

Conclusion: Single dose of TCA 85% in topical solution was able to destroy the normal cervical tissue with a deeper mean depth than the mean depth of CIN III in squamous epithelium.

Human Papillomavirus Persistence and Association With Recurrent Cervical Intraepithelial Neoplasia After Cryotherapy vs Loop Electrosurgical Excision Procedure Among HIV-Positive Women: A Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE

Persistence of cervical high-risk human papillomavirus (hrHPV) after treatment for cervical intraepithelial neoplasia grade 2 or higher (CIN2+) has not been compared between cryotherapy and loop electrosurgical excision procedure (LEEP) among HIV-positive women.

OBJECTIVE

To evaluate whether cryotherapy or LEEP is more effective at clearing hrHPV and whether persistent hrHPV is associated with CIN2+ recurrence among HIV-positive women.

DESIGN, SETTING, AND PARTICIPANTS

This is a secondary analysis of a randomized clinical trial conducted among women with HIV, hrHPV, and CIN2+ in Nairobi, Kenya. From June 2011 to September 2016, 354 HIV-positive women with CIN2+ disease had hrHPV cervical samples collected before and after treatment with cryotherapy or LEEP. Data were analyzed from September 2018 to January 2021.

INTERVENTIONS

Women were randomized 1:1 to receive cryotherapy or LEEP and were followed up every 6 months for 24 months with hrHPV cervical swab and Papanicolaou test with confirmatory biopsy.

MAIN OUTCOMES AND MEASURES

The main outcomes of this analysis were hrHPV positivity defined as having 1 of 12 hrHPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59) and disease recurrence defined as CIN grade 2 or higher as determined with cervical biopsy.

RESULTS

A total of 354 HIV-positive women with CIN2+ were included in the study; mean (SD) age was 37 (8) years in the cryotherapy arm and 38 (9) years in the LEEP arm. Baseline hrHPV prevalence was 90% (160 of 177) in the cryotherapy arm and 94% (166 of 177) in the LEEP arm (P = .24), and the most common hrHPV types detected were 16 (87 of 326 [27%]), 58 (87 of 326 [27%]), 35 (86 of 326 [26%]), 52 (66 of 326 [20%]), and 18 (56 of 325 [17%]). Over 24 months, clearance of hrHPV was significantly higher among those who underwent LEEP compared with cryotherapy (hazard ratio, 1.40; 95% CI, 1.03-1.90; P = .03). In multivariable analysis, hrHPV type-specific persistence at 12-month follow-up was significantly associated with CIN2+ recurrence from 12 months to 24 months (adjusted hazard ratio, 4.70; 95% CI, 2.47-8.95; P < .001). Performance of hrHPV testing at 12 months for recurrent CIN2+ was 93% sensitivity, 46% specificity, 38% positive predictive value, and 95% negative predictive value.

CONCLUSIONS AND RELEVANCE

In this secondary analysis of a randomized clinical trial, HIV-positive women who received LEEP were more likely to clear hrHPV infection compared with those undergoing cryotherapy, reinforcing the efficacy of LEEP in this population. Persistent hrHPV was significantly associated with recurrent CIN2+, suggesting that LEEP's benefits may be related in part to its ability to clear hrHPV infection. Screening for hrHPV infection after treatment among HIV-positive women may be used to rule out recurrent CIN disease given its high sensitivity and negative predictive value.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01298596.

Intratumoral Photosensitizer Delivery and Photodynamic Therapy

Photodynamic therapy (PDT) is a two-step procedure that involves the administration of special drugs, commonly called photosensitizers, followed by the application of certain wavelengths of light. The light activates these photosensitizers to produce reactive molecular species that induce cell death in tissues. There are numerous factors to consider when selecting the appropriate photosensitizer administration route, such as which part of the body is being targeted, the pharmacokinetics of photosensitizers, and the formulation of photosensitizers. While intravenous, topical, and oral administration of photosensitizers are widely used in preclinical and clinical applications of PDT, other administration routes, such as intraperitoneal, intra-arterial, and intratumoral injections, are gaining traction for their potential in treating advanced diseases and reducing off-target toxicities. With recent advances in targeted nanotechnology, biomaterials, and light delivery systems, the exciting possibilities of targeted photosensitizer delivery can be fully realized for preclinical and clinical applications. Further, in light of the growing burden of cancer mortality in low and middle-income countries and development of low-cost light sources and photosensitizers, PDT could be used to treat cancer patients in low-income settings. This short article introduces aspects of interfaces of intratumoral photosensitizer injections and nano-biomaterials for PDT applications in both high-income and low-income settings but does not present a comprehensive review due to space limitations.

Optimizing ethyl cellulose-ethanol delivery towards enabling ablation of cervical dysplasia

In low-income countries, up to 80% of women diagnosed with cervical dysplasia do not return for follow-up care, primarily due to treatment being inaccessible. Here, we describe development of a low-cost, portable treatment suitable for such settings. It is based on injection of ethyl cellulose (EC)-ethanol to ablate the transformation zone around the os, the site most impacted by dysplasia. EC is a polymer that sequesters the ethanol within a prescribed volume when injected into tissue, and this is modulated by the injected volume and delivery parameters (needle gauge, bevel orientation, insertion rate, depth, and infusion rate). Salient injection-based delivery parameters were varied in excised swine cervices. The resulting injection distribution volume was imaged with a wide-field fluorescence imaging device or computed tomography. A 27G needle and insertion rate of 10 mm/s achieved the desired insertion depth in tissue. Orienting the needle bevel towards the outer edge of the cervix and keeping infusion volumes ≤ 500 µL minimized leakage into off-target tissue. These results guided development of a custom hand-held injector, which was used to locate and ablate the upper quadrant of a swine cervix in vivo with no adverse events or changes in host temperature or heart rate. After 24 h, a distinct region of necrosis was detected that covered a majority (> 75%) of the upper quadrant of the cervix, indicating four injections could effectively cover the full cervix. The work here informs follow up large animal in vivo studies, e.g. in swine, to further assess safety and efficacy of EC-ethanol ablation in the cervix.

Effect of Cryotherapy vs Loop Electrosurgical Excision Procedure on Cervical Disease Recurrence Among Women With HIV and High-Grade Cervical Lesions in Kenya: A Randomized Clinical Trial

Importance

The World Health Organization recommends cryotherapy or loop electrosurgical excision procedure (LEEP) for histologically confirmed cervical intraepithelial neoplasia (CIN) grade 2 or higher regardless of HIV status. Cryotherapy is more feasible in resource-limited settings but may be less effective for women living with HIV.

Objective

To evaluate whether cryotherapy or LEEP is a more effective treatment for high-grade cervical lesions among women with HIV.

Design, Setting, and Participants

Single-center randomized trial conducted among women with HIV and CIN grade 2 or 3. From June 2011 to September 2016, women with HIV in Kenya underwent cervical screening with Papanicolaou testing and confirmatory biopsy. The final date on which a study procedure was administered was September 7, 2016.

Interventions

Women with HIV infection and CIN grade 2 or 3 were randomized 1:1 to receive cryotherapy (n = 200) or LEEP (n = 200) and were followed up every 6 months for 24 months with a Papanicolaou test and confirmatory biopsy.

Main Outcome and Measures

The primary outcome was disease recurrence, defined as CIN grade 2 or higher on cervical biopsy, during the 24-month follow-up period.

Results

Among 400 women who were randomized (median age, 37.4 [interquartile range, 31.9-43.8] years), 339 (85%) completed the trial. Over 2 years, 60 women (30%) randomized to cryotherapy had recurrent CIN grade 2 or higher vs 37 (19%) in the LEEP group (relative risk, 1.71 [95% CI, 1.12-2.65]; risk difference, 7.9% [95% CI, 1.9%-14.0%]; P = .01). Adverse events occurred in 40 women (45 events, including change in pathology and death due to other causes) in the cryotherapy group and in 30 women (38 events, including change in pathology and unrelated gynecological complications) in the LEEP group.

Conclusions and Relevance

In this single-center study of women with HIV infection and CIN grade 2 or 3, treatment with LEEP compared with cryotherapy resulted in a significantly lower rate of cervical neoplasia recurrence over 24 months. Cost-effectiveness analysis is necessary to determine whether the additional benefit of LEEP represents an efficient use of the additional resources that would be required.

Trial Registration

ClinicalTrials.gov Identifier: NCT01298596.

Ablative Therapies for Cervical Intraepithelial Neoplasia in Low-Resource Settings: Findings and Key Questions

Barriers to access for cervical precancer care in low-resource settings go beyond cost. Gas-based cryotherapy has emerged as the standard treatment in these areas, but there are barriers to this technology that have necessitated the development and implementation of affordable and portable alternatives. This review identifies knowledge gaps with regard to technologies primarily used in low-resource settings, including standard cryotherapy, nongas-based cryotherapy, and thermoablation. These gaps are addressed using evidence-based guidelines, patient and provider acceptability, long-term obstetric outcomes, and treatment of women with HIV infection. This review highlights the need for prospective studies that compare ablative methods, especially given the increasing use of thermoablation.

Development of enhanced ethanol ablation as an alternative to surgery in treatment of superficial solid tumors

While surgery is at the foundation of cancer treatment, its access is limited in low-income countries. Here, we describe development of a low-cost alternative therapy based on intratumoral ethanol injection suitable for resource-limited settings. Although ethanol-based tumor ablation is successful in treating hepatocellular carcinomas, the necessity for multiple treatments, injection of large fluid volumes, and decreased efficacy in treatment of non-capsulated tumors limit its applicability. To address these limitations, we investigated an enhanced ethanol ablation strategy to retain ethanol within the tumor through the addition of ethyl cellulose. This increases the viscosity of injected ethanol and forms an ethanol-based gel-phase upon exposure to the aqueous tumor environment. This technique was first optimized to maximize distribution volume, using tissue-simulating phantoms. Then, chemically-induced epithelial tumors in the hamster cheek pouch were treated. As controls, pure ethanol injections of either four times or one-fourth the tumor volume induced complete regression of 33% and 0% of tumors, respectively. In contrast, ethyl cellulose-ethanol injections of one-fourth the tumor volume induced complete regression in 100% of tumors. These results contribute to proof-of-concept for enhanced ethanol ablation as a novel and effective alternative to surgery for tumor treatment, with relevance to resource-limited settings.

Comparison of the depth of tissue necrosis between double-freeze and single-freeze nitrous oxide-based cryotherapy

Background:

Cryotherapy is one the methods of treating cervical premalignant lesions. It is particularly suitable for low-resource countries because of it is relative cheaper, has low cost of maintenance, ease of use and that does not require electricity which is in short supply in many rural areas of developing countries where the incidence and mortality from cervical cancer is very high. In this study we compared single and double freezing on the cervices of women admitted for hysterectomy for benign conditions using Nitrous-based cryotherapy.

Materials and Methods:

Patients admitted for elective hysterectomy for benign gynaecological conditions were randomized into two arms. The first group had single freeze cryotherapy while the second arm received double freeze cryotherapy. The cervices were examined 24 hours later to determine the depth of tissue necrosis.

Results:

In this comparative study, the depth of tissue necrosis was deeper with double freeze compared with single freeze. Also in both arms, the depth of necrosis was deeper on anterior lips than on posterior lips of the cervix.

Conclusion:

Double freeze technique achieve more depth of tissue necrosis than single-freeze on both anterior and posterior lips of the cervix.

Comparison of depth of necrosis using cryotherapy by gas and number of freeze cycles

OBJECTIVE

This study aimed to establish the noninferiority of a single-freeze application with CO2 or N2O compared with the standard double freeze with N2O for cryotherapy treatment.

MATERIALS AND METHODS

Sixty women undergoing hysterectomy for reasons other than cervical cancer or precancer were randomized to 1 of 3 techniques as follows: (1) double freeze with N2O, (2) single freeze with N2O, or (3) single freeze with CO2. The cervix was separated and cut into anterior and posterior segments, and the deepest area of necrosis was recorded. Comparisons were made using regression analysis. The margin of noninferiority was defined as 0.8 mm.

RESULTS

On the anterior lip, a single freeze with N2O was noninferior to a double freeze of the same gas, but on the posterior lip, the single freeze was not. The single freeze of CO2 did not provide sufficient depth of necrosis in either lip to infer noninferiority versus the double freeze with N2O.

CONCLUSIONS

A single freeze with N2O is noninferior to a double-freeze technique in the anterior but not the posterior lip. However, the result for posterior lips was close to reaching statistical significance. In addition, CO2 had approximately 1 mm shallower depth of necrosis compared with N2O techniques; however, the clinical implications are unknown. Given the extensive use of CO2 globally, further clinical evaluation is needed.

Clinical response to glycyrrhizinic acid in genital infection due to human papillomavirus and low-grade squamous intraepithelial lesion

Human papilloma virus (HPV) can infect any of the mucosal areas of the body and cause cervical cancer. Until recently, no specific treatments were available for this condition; therefore, any damaged tissue had to be removed or destroyed, which may have presented obstetrical repercussions for some women. Recently, new drugs have been developed that have shown to be effective for the cure of HPV infection. Glycyrrhizinic acid (GA) has shown fewer side effects and its systemic use makes it possible to reach difficult-to-treat lesions. The purpose of this study was to evaluate the clinical outcome of GA to eliminate the epithelial lesion and HPV. We carried out a longitudinal, descriptive study that included women of reproductive age who were diagnosed with HPV associated with low-grade squamous intraepithelial lesion (LSIL). Subjects began treatment based on GA using two routes of administration - systemic (oral) and topical (spray) - with assessments every month to determine the clinical changes of the lesions through colposcopy and Papanicolaou (Pap) smear. Simple statistics were used along with two-tailed Student's t-test; P<0.05 was considered statistically significant before and after treatment. There were 70 eligible patients, of whom 62 fulfilled the inclusion criteria. Age of subjects was 27.8±9.5 years. At the time of the study, 100% of the patients had HPV infection, 40% were associated with LSIL, and only 16% used a barrier contraceptive (condom) method. Resolution was achieved in all patients from 4 weeks of treatment initiation and improvement was achieved in the majority of patients at 12 weeks (74%) (P<0.001). However, there was persistence of LSIL in 27.7% of patients and only one patient progressed to cervical intraepithelial neoplasia (CIN) II. The use of GA proved to be effective in resolving clinical HPV lesions. For cervical lesions with epithelial changes (LSIL), treatment may be required for a longer period as with other drugs used for this infection, as well as monitoring for at least 1 year according to the natural evolution of the disease.

Growth suppression of four cancer cells by hyperbaric nitrous oxide and methotrexate

BACKGROUND

Nitrous oxide concentration is easily controlled by respiratory ventilation. It suppresses bone marrow via the inhibition of thymidylate synthesis. The aim of this work was to determine the optimal pressure and exposure duration of nitrous oxide, as well as methotrexate concentration that maximizes the suppression of 4 cancer cells: CCRF-CEM, K562, A549 and MDA-MB-231.

METHODS

Each cancer cell was cultured in a hyperbaric chamber at 1, 2 and 3 atmosphere of 74% nitrous oxide for 24, 48, and 72 hours at 0, 0.3, 0.7, 1, 2, 5 and 10 microM methotrexate (MTX), respectively. The results were expressed in the ratio of the number of cancer cells cultured under specific conditions (S cells) to that under normal conditions (N cells).

RESULTS

The S/N ratio of CCRF-CEM cells was 87.4% in 24-hour culture, 95.0% in 48-hour culture and 115.9% in 72-hour culture (P < 0.05). The S/N ratio of K562 cells was 103.6% at 1 atm, 102.4% at 2 atm and 115.6% at 3 atm (P < 0.05). The S/N ratio of A549 cells was 94.3% at 1 atm, 94.1% at 2 atm, 99.3% at 3 atm, 96.2% in 24-hour culture, 99.2% in 48-hour culture and 99.3% in 72-hour culture (P > 0.05). However, the S/N ratio of MDA-MB 231 cells was 66.9% in 24-hour culture, 83.1% in 48 hour culture and 87.8% in 72-hour culture (P < 0.05).

CONCLUSIONS

Only the growth of the MDA-MB-231 cells was significantly reduced after a longer exposure time to nitrous oxide, but those of the other cells were not.

Human papillomavirus infection and the primary and secondary prevention of cervical cancer

A wealth of evidence has led to the conclusion that virtually all cases of cervical cancer are attributable to persistent infection by a subset of human papillomavirus (HPV) types, especially HPV type 16 (HPV-16) and HPV-18. These HPV types also cause a proportion of other cancers, including vulvar, vaginal, anal, penile, and oropharyngeal cancers. Although cervical cancer screening, primarily with the Papanicolaou (Pap) smear, has reduced the incidence of this cancer in industrialized countries, cervical cancer remains the second most common cause of death from cancer in women worldwide, because the developing world has lacked the resources for widespread, high-quality screening. In addition to advances in Pap smear technology, the identification of HPV as the etiologic agent has produced 2 recent advances that may have a major impact on approaches to reduce the incidence of this disease. The first is the development of a preventive vaccine, the current versions of which appear to prevent close to 100% of persistent genital infection and disease caused by HPV-16 and HPV-18; future second-generation vaccines may be able to protect against oncogenic infections by a broader array of HPV types. The second is the incorporation of HPV testing into screening programs. In women aged >30 years, HPV testing can identify high-grade cervical intraepithelial neoplasia earlier than Pap smears with acceptable rates of specificity. These results, together with the high sensitivity of HPV testing, suggest that such testing could permit increased intervals for screening. An inexpensive HPV test in development, if successful, may be incorporated as part of an economically viable 'screen-and-treat' approach in the developing world. The manner in which vaccination and screening programs are integrated will need to be considered carefully so that they are efficient in reducing the overall incidence of cervical cancer.

Perinatal mortality and other severe adverse pregnancy outcomes associated with treatment of cervical intraepithelial neoplasia: meta-analysis

OBJECTIVE

To assess the relative risk of perinatal mortality, severe preterm delivery, and low birth weight associated with previous treatment for precursors of cervical cancer.

DATA SOURCES

Medline and Embase citation tracking from January 1960 to December 2007. Selection criteria Eligible studies had data on severe pregnancy outcomes for women with and without previous treatment for cervical intraepithelial neoplasia. Considered outcomes were perinatal mortality, severe preterm delivery (<32/34 weeks), extreme preterm delivery (<28/30 weeks), and low birth weight (<2000 g, <1500 g, and <1000 g). Excisional and ablative treatment procedures were distinguished.

RESULTS

One prospective cohort and 19 retrospective studies were retrieved. Cold knife conisation was associated with a significantly increased risk of perinatal mortality (relative risk 2.87, 95% confidence interval 1.42 to 5.81) and a significantly higher risk of severe preterm delivery (2.78, 1.72 to 4.51), extreme preterm delivery (5.33, 1.63 to 17.40), and low birth weight of <2000 g (2.86, 1.37 to 5.97). Laser conisation, described in only one study, was also followed by a significantly increased chance of low birth weight of <2000 g and <1500 g. Large loop excision of the transformation zone and ablative treatment with cryotherapy or laser were not associated with a significantly increased risk of serious adverse pregnancy outcomes. Ablation by radical diathermy was associated with a significantly higher frequency of perinatal mortality, severe and extreme preterm delivery, and low birth weight below 2000 g or 1500 g.

CONCLUSIONS

In the treatment of cervical intraepithelial neoplasia, cold knife conisation and probably both laser conisation and radical diathermy are associated with an increased risk of subsequent perinatal mortality and other serious pregnancy outcomes, unlike laser ablation and cryotherapy. Large loop excision of the transformation zone cannot be considered as completely free of adverse outcomes.