Thin variant of high-grade squamous intraepithelial lesion - relationship with high-risk and possibly carcinogenic human papilloma virus subtypes and somatic cancer gene mutations

Invasive Squamous Cell Carcinoma of the Cervix: A Review of Morphological Appearances Encountered in Human Papillomavirus-associated and Papillomavirus-independent Tumors and Precursor Lesions

Cervical cancer is the fourth most common cancer among women globally. Historically, human papillomavirus (HPV) infection was considered necessary for the development of both precursor and invasive epithelial tumors of the cervix; however, studies in the last decade have shown that a significant proportion of cervical carcinomas are HPV-independent (HPVI). The 2020 World Health Organization (WHO) Classification of Female Genital Tumors separates both squamous cell carcinomas (SCCs) and endocervical adenocarcinomas (ECAs) by HPV status into HPV-associated (HPVA) and HPVI tumors. The classification further indicates that, in contrast to endocervical adenocarcinomas, HPVI and HPVA SCCs cannot be distinguished by morphological criteria alone and suggests that HPV testing or correlates thereof are required for correct classification. Moreover, while HPVA SCC precursor lesions (ie, high-grade squamous intraepithelial lesion) are well known and characterized, precursors to HPVI SCCs have only been described recently in a small number of cases. We studied 670 cases of SCCs from the International Squamous Cell Carcinoma Project (ISCCP) to analyze the reproducibility of recognition of invasive SCC growth patterns, presence of lymphovascular space invasion, tumor grade, and associations with patient outcomes. Consistent with previous studies, we found histologic growth patterns and tumor types had limited prognostic implications. In addition, we describe the wide morphologic spectrum of HPVA and HPVI SCCs and their precursor lesions, including tumor growth patterns, particular and peculiar morphologic features that can lead to differential diagnoses, and the role of ancillary studies in the diagnosis of these tumors.

Acquisition of Genetic Aberrations During the Progression of High-Grade Intraepithelial Lesions/Micro-Invasive Squamous Cancers to Widely Invasive Cervical Squamous Cell Cancer

CONTEXT.—

Acquisition of genetic aberrations during cervical carcinogenesis in individual patients is poorly documented.

OBJECTIVE.—

To provide a comparative analysis of high-grade squamous intraepithelial lesions (n = 7) and pT1a squamous cancers (n = 1) and their recurrences, subsequent widely invasive cancers, and metastases developed during 1-24 years.

DESIGN.—

Archival tissues of 8 patients were analyzed immunohistochemically for reserve-cell origin, human papillomavirus genotypes, mutations in 50 cancer genes, and chromosomal copy number variations.

RESULTS.—

Intraepithelial lesions arose either from cytokeratin 17- or 7-expressing reserve cells. All preinvasive and invasive tumors carried human papillomavirus high-risk genotypes and lacked somatic mutations. Chromosomal copy number variations were identified in all intraepithelial lesions and invasive cancers. Four of 8 high-grade intraepithelial lesions progressed to invasive cancer after incomplete treatment, and 4 of 8 invasive cancers arose de novo after in sano resection. Four of 8 cancers carried mutations with high mutational frequency (PIK3CA E545K [n = 2]; PIK3CA and SMAD1 [n = 1]; HRAS, RB1, and EGFR [n = 1]), as did their corresponding regional metastases. One nonmetastasized cancer had a subclonal PIK3CA mutation, and an initially nonmutated, low-stage cancer developed ovarian metastases with PIK3CA amplification. One patient had neither mutations nor metastases. The patient with treated PIK3CA E545K-mutated pT1a cancer developed a subsequent nonmutated intraepithelial lesion that progressed to invasive cancer with a subclonal PIK3CA-H1047R mutation. Cancer-related deaths in 4 of 8 (50%) patients occurred independent of mutational status or metastatic disease.

CONCLUSIONS.—

Recurrences arose after persistent or de novo human papillomavirus infection of residual reserve cells or squamous metaplasia. Activating driver mutations were identified in invasive cancers only. High mutational load correlated with metastases, which in turn represented clonal disease.

Underdiagnosis of cervical intraepithelial neoplasia by colposcopy and its association with thin high‑grade squamous intraepithelial lesions

The relationship between the thickness of the epithelium and the colposcopic diagnosis is controversial. The present study was conducted to determine whether colposcopic underdiagnosis of cervical intraepithelial neoplasia (CIN) is associated with thin high-grade squamous intraepithelial lesions (HSILs) of the cervix. A total of 136 cases of HSIL verified by pathological biopsy at Peking University People's Hospital between June and October 2021 were retrospectively analyzed; 79 cases were CIN2 and 57 cases were CIN3. The number and thickness of epithelial layers were analyzed using colposcopic impressions. In the low-grade colposcopic impression group, the number of epithelial layers (12.8±4.2 vs. 17.8±4.2) and epithelial thickness (105.2±41.9 µm vs. 150.3±50.0 µm) of CIN2 lesions were significantly lower compared with the high-grade colposcopic impression group; however, the differences for CIN3 were not statistically significant. CIN2 lesions had significantly fewer (12.8±4.2 vs. 17.2±5.4) and thinner (105.2±41.9 µm vs. 140.4±48.6 µm) epithelial layers than CIN3 lesions in the low-grade colposcopic impression groups. In the high-grade colposcopic impression group, however, there were no significant differences in the number or thickness of epithelial layers between CIN2 and CIN3. In 12 cases of thin HSILs, 91.6% of the colposcopic impressions were low-grade. Thin HSILs are likely associated with underdiagnosed colposcopic findings, particularly for CIN2. Thin HSILs usually present with small to minute lesions and lack the typical colposcopic appearance of classic HSIL, which may help to explain why thin HSILs are easily underestimated under colposcopy.

Elimination of reserve cells for prevention of HPV-associated cervical cancer

Human papilloma viruses (HPV), that are causative for most squamous cell cervical cancers (SCC), have a simple structure with only a few genes (six early and two late genes). Two of the early HPV genes (E6 and E7) are capable of transforming normal squamous epithelium into cancer. In the last 10 years, a controversial discussion arose as to which cells are primarily involved in cervical carcinogenesis. Virologists traditionally use a research model of stratified squamous epithelium, a permissive environment for completion of a full HPV-life cycle. Basic insights on HPV tropism, HPV life cycle, HPV-uptake, HPV-replication, HPV-gene expression were gained from this model. Stratified squamous epithelium, however, is a low-risk area for SCC. Most SCC develop in an area of endocervical columnar epithelium that undergoes squamous metaplasia. SCC arise after infection of immature squamous metaplasia, proliferating reserve cells/reserve cell hyperplasia and reserve cells of the endocervical columnar epithelium. Study models investigating this pathway of carcinogenesis do not exist and therapeutic consequences deduced from this knowledge are lacking. This review describes in detail cervical carcinogenesis after HPV infection of subcolumnar reserve cells and discusses new intervention strategies for patients. The WHO-launched global strategy to eliminate HPV-associated cervical cancer builds primarily on prophylactic vaccination, screening and treatment. New insights in cervical pathogenesis, may assist in reaching this ambitious WHO goal.

Cervical Precancers Originate From Infected Proliferating Reserve Cells: A Comparative Histologic and Genetic Study of Thin and Thick High-grade Squamous Intraepithelial Lesions

Human papillomavirus (HPV)-induced invasive cervical squamous cell cancer (SCC) develop via high-grade squamous intraepithelial lesion (HSIL). In contrast to classic thick HSIL, thin HSIL (≤9 cell layers) are poorly documented. This study compares histology, HPV genotypes, and aberrations in 50 cancer genes of 45 thin HSIL to 45 thick HSIL, 20 pT1a SCC, and 40 ≥pT1b SCC. Thin HSIL arose from proliferating reserve cells within endocervical epithelium or immature metaplasia throughout the transformation zone after infection with high-risk HPV genotypes (36/45; 80%), and 20% non-high-risk HPV genotypes compared with 2.5% thick HSIL, pT1a SCC, and ≥pT1b SCC. Thin HSIL were multifocal proliferations with varying epithelial thickness between 1 and 2 to 9 cell layers, with occasional transitions to thick HSIL or concomitant lesions of thick HSIL. Overall, 40% thin HSIL were located distant to and most thick HSIL occurred near or at the squamocolumnar junction. Only 20% thick HSIL showed koilocytosis. All HSIL lacked somatic gene mutations, compared with 30% pT1a and 55%≥pT1b SCC. Overrepresented rare germline variants in the MET, JAK3, and FGFR3 genes occurred in all patient groups. In summary, thin and thick HSIL arose independently of somatic gene mutations. The maturation level of the squamous epithelium at the time of transforming infection determines if a thick HSIL develops directly from HPV-infected proliferating reserve cells via thin HSIL or in stratified glycogenated squamous epithelium via low-grade squamous intraepithelial lesion. These observations raise doubts about the biological relevance of separation into thin and thick HSIL. The oncogenic potential of HPV genotypes but also germline variants may influence the natural history.

Driver gene mutations in micro-invasive cervical squamous cancers have no prognostic significance

OBJECTIVE

To evaluate the prevalence of somatic gene mutations in different stages of cervical carcinogenesis placing special emphasis on micro-invasive pT1a cervical squamous cell cancers (SCC).

METHODS

Micro-dissected samples of 32 micro-invasive pT1a and 55 ≥ pT1b SCC were evaluated by next generation sequencing of 50 cancer genes (cancer hot spot panel).

RESULTS

At primary diagnosis, 8/32 (25%) pT1a SCC, 10/28 (36%) pT1b SCC and 15/27 (56%) pT2/3 SCC carried somatic gene mutations. The most commonly affected gene was the PIK3CA gene in hot spot regions E545K and E453K in 5/8 (62%) pT1a SCC, 7/15 (70%) pT1b SCC and 10/15 (66%) pT2/3 SCC followed by FBXW7 (n = 4), KRAS and RB1 (n = 2 each). ERBB2, APC, ATM, MLP gene mutations occurred only once. Solitary activating oncogenic somatic mutations dominated over tumor suppressor mutation in 88% pT1a, 80% pT1b and 60% pT2/3 SCC. Concomitant mutations involved typically an activating oncogenic mutation and an inactivating tumor-suppressor gene mutation. All patients with pT1a SCC are alive without evidence of disease after surgical treatment, independent of mutational status or lympho-vascular space invasion.

CONCLUSIONS

Activating oncogenic gene mutations, in particular in the PIK3CA gene, occur early in cervical carcinogenesis. Although driver gene mutations bestow tumor cells with a growth advantage, early detection and complete removal of all cancer cells - with or without somatic gene mutations - are essential for cure. In contrast to advanced inoperable SCC, where PIK3CA driver gene mutations carry an adverse prognosis, the mutational status in surgically treated micro-invasive SCC is prognostically irrelevant.

Human papillomavirus E6E7 mRNA and TERC lncRNA in situ detection in cervical scraped cells and cervical disease progression assessment

Background

Human papillomavirus screen in female cervical cells has demonstrated values in clinical diagnosis of precancerous lesions and cervical cancers. Human papillomavirus tests of cervical cells by utilizing Polymerase Chain Reaction (PCR) method provides human papillomavirus infection status however no further virus in situ information. Although it is well known that the tests of human papillomavirus E6/E7 RNA location in infected cervical cells and cell internal malignancy molecular will provide clues for gynecologists to evaluate disease progression, there are technique difficulties to preserve RNAs in cervical scraped cells for in situ hybridization.

Methods

In current study, after developing a cervical cell collection and preparation method for RNA in situ hybridization, we captured the chance to screen 98 patient cervical cell samples and detected human papillomavirus E6/E7 mRNAs of high-risk subtypes, low-risk subtypes and long non-coding RNA (lncRNA) TERC in the cells.

Results

There were 69 samples exhibited consistence between human papillomavirus PCR and human papillomavirus RNA in situ hybridization results in cervical collected cells. Among them, 23 were both positive and 46 were both negative. In the rest 29 samples, 8 were HPV RNAscope positive, either high risk or low risk subtypes, however HPV PCR negative. Another 9 samples were HPV PCR results positive whereas RNAscope negative. The last 12 samples were HPV positive detected by both RNAscope and PCR methods, however inconsistent between high-risk and low-risk subtypes. In RNAscope positive samples, viral E6/E7 mRNAs were observed to distribute in cervical scraped cell nucleus and cytoplasm. Moreover, HPV viral RNA gathered clusters were observed outside of cells through human papillomavirus RNA in situ hybridization detection. Varied numbers of human papillomavirus infective cells were detected by RNAscope assay in different patients even though they were all human papillomavirus high-risk subtype positive discovered by human papillomavirus PCR results. A cell malignancy related long non-coding RNA, TERC, has been detected in seven patient samples. The patient follow-up information was further analyzed with RNAscope results which indicated a combination of RNAscope positive signals of TERC and human papillomavirus high risk signals in more than 10 cells (cytoplasm or nucleus) may connect with cervical lesion fast progression which deserves further studies in the future.C

Conclusions

Taken together, current study has provided an observable clue for gynecologists to evaluate human papillomavirus infection stage and cell malignancy status which may contribute for assessment of cervical disease progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01696-9.

The origin of Human Papillomavirus (HPV) - induced cervical squamous cancer

Most research models of HPV-associated squamous cervical carcinogenesis focus on stratified glycogenated squamous epithelium, a permissive environment for HPV-life-cycle completion, while immature squamous metaplastic epithelium and reserve cells as targets of HPV-infection have received less attention. Subcolumnar reserve cells of urogenital sinus origin with a CK17/p63-phenotype serve as the primary stem cell for squamous metaplasia. The area of manifest or potential squamous metaplasia, referred to as transformation zone, is the site where most squamous cancers occur after a transforming HPV infection of proliferating reserve cells and/or metaplastic epithelium. Improper use of terminology, in particular confusion of transformation zone with transition zone (synonymous: squamous-columnar junction or SCJ), as well as poorly substantiated postulates of a stem cell niche at the squamous-columnar junction with 'embryonic stem cell markers' have complicated understanding of HPV-related squamous carcinogenesis. Reserve cells as target cells and reservoirs of HPV should move into future research focus.

The immune landscape during the tumorigenesis of cervical cancer

Objective

Deciphering the determinants of the intralesional immune reaction in cervical carcinogenesis may be conducive to improving the understanding of the disease and then improve outcomes.

Methods

Public gene‐expression data and full clinical annotation were searched in Gene Expression Omnibus in the joint analysis of the array‐based four eligible cohorts. The infiltrating estimation was quantified using microenvironment cell populations‐counter algorithm and absolute‐mode CIBERSORT and verified by flow cytometry analysis. An unsupervised classification on immune genes strongly associated with progression, designated by linear mixed‐effects regression. We determined immune response and signaling features of the different developmental stages and immune phenotypes by functional annotation and systematically correlated the expression of immune checkpoints with cell‐infiltrating characteristics.

Results

We identified the lesion‐intrinsic immunosuppression mechanism was triggered at precancerous stages, such as genome instability and mutation, aerobic glycolysis, activation of proto‐oncogene pathways and so forth. Predominant innate and adoptive cells were increasing from normalcy to cancer (B cell, total T cell, regulatory T cells [Tregs], monocytes, neutrophils, and M2‐like macrophages) together with the decrease of CD4⁺ T cell and CD8⁺ T cell through the development of cervical cancer. Immune escape initiated on the expression of immunosuppressive molecules from high‐grade squamous intraepithelial lesions (HSIL) and culminated in squamous cell carcinoma (SCC). Of note, the expression of immune checkpoints was escalated in the immune‐hot and immune‐warm phenotype largely encompassed by HSIL and SCC under the stress of both activated and suppressive immune responses.

Conclusions

Immune surveillance is unleashing from low‐grade squamous intraepithelial lesions onwards and immune‐suppression mechanisms are triggered in HSIL. Thorough knowledge of the immune changing pattern during cervical tumorigenesis contributes to finding the potential therapeutic targets to susceptive patients towards immune checkpoints inhibitors.

Incidence, persistence and clearance of cervical human papillomavirus among women in Guangdong, China 2007-2018: A retrospective cohort study

BACKGROUND

Previous studies showed the incidence, persistence and clearance of cervical human papillomavirus (HPV) among women varies from regions. There is no study on dynamic changes of HPV infection among women in Guangdong.

METHODS

It is a retrospective cohort study that included gynecological outpatients aged ≥15 years and retested for HPV within 24 months in Guangdong Women and Children Hospital to estimate HPV incidence, persistence and clearance. Outcomes were estimated through the proportion of HPV incidence, persistence and clearance in HPV-negative or HPV-positive women. Moreover, we examined HPV incidence, persistence and clearance among women who retested in four calendar periods: 0-6, 6-12, 12-18, 18-24 months after the first test.

RESULTS

33,328 gynecological outpatients were included in our study. Incidence rates of any HPV, high-risk (HR) HPV and low-risk (LR) HPV were 10.58%, 8.68% and 4.83%. The most common incident HR HPV were HPV52 (2.69%), HPV16 (1.23%) and HPV58 (1.23%). Persistence rates of any HPV, HR HPV and LR HPV were 47.55%, 42.77% and 33.88%. HPV52 (42.33%), HPV58 (40.74%) and HPV68 (32.36%) were commonly found persistent types. And clearance rates of any HPV, HR HPV and LR HPV were 52.44%, 57.23% and 66.12%.The lowest clearance rates were observed for HPV52 (57.67%), HPV68 (67.64%) and HPV39 (68.56%). HPV incidence and persistence were higher among women aged 15-19 years and ≥55 years. HPV incidence and persistence were found higher among women who retested within 6 months than others in other periods.

CONCLUSIONS

HPV52, 58, 68, and 39 were the more likely to cause incident and persistent infection, and less likely to be cleared among women in Guangdong. HPV incidence and persistent infection were higher among women aged both younger and older women compared to middle aged women. HPV retesting period may impact the detection of HPV incidence, persistence and clearance.

Possibly carcinogenic HPV subtypes are a cause of HSIL and negative clinical HPV tests - A European prospective single center study

OBJECTIVE

To correlate p16^ink4a positive cervical precancers of 388 consecutive patients from a single European center with the preceding clinical HPV-DNA and HPV E6/E7 mRNA screening test.

METHOD

374/388 patients had a HSIL (CIN 2/3) and 14/388 AIS (6 pure and 8 combined AIS/HSIL). Lesional tissues of HSIL/AIS with negative Cobas and/or Aptima HPV tests underwent HPV genotyping with CHIPRON HPV 3.5 LCD-array. Selected cases were subjected to a cancer hot spot analysis.

RESULTS

The Aptima test missed 10/388 (2.6%) and the Cobas test seven of 388 (1.8%) precancers associated HPV-HR. Both HPV tests were negative in 20/374 precancers (5.3%; 17 HSIL/CIN3, two HSIL/CIN2, one AIS). Due to insufficient DNA four of 20 double negative cases (three HSIL, one AIS) were not genotyped. In the remaining cases, two of 20 (10%) HSIL genotyping detected HR-HPV subtypes. 10/20 (50%) HSIL were associated with possibly carcinogenic and low risk HPV (four x HPV73, three x HPV 53, one x HPV 82, one x HPV 67 and one x HPV 6), all of which are not included in both HPV tests. Two of 20 (10%) HSIL were negative with all HPV tests; one of these HSIL had a somatic PIK3CA gene mutation and the other had a single nucleotide variant in the APC gene. Three of 20 HSIL (15%) were thin HSIL (≤9 cell layers thick).

CONCLUSIONS

Possibly carcinogenic HPV subtypes not included in the clinical HPV tests may account for the small gap of missed HSIL in clinical HPV screening. True HPV negative HSIL are exceedingly rare. Expanding HPV testing to include more possibly carcinogenic HPV subtypes may further reduce cervical cancer.

Changes in the genetic landscape during the malignization of high grade squamous intraepithelial lesion into cervical cancer

In 5 patients, a change in the genetic landscape from HPV16 positive high-grade squamous intraepithelial lesion (HSIL) to squamous cervical cancer was traced, which occurred in these patients within the period from 7 months to 5 years after diagnosing HSIL.

MATERIALS AND METHODS

The DNA from paraffin blocks of dysplasia tissue and the tumor that emerged afterwards was used for the study, which was analyzed using the OncoScan FFPE microarray Assay Kit Affymetrix (USA) for genome-wide determination of gene abundance and 65 key somatic driver mutations of oncogenes and tumor suppressor genes.

RESULTS

In the study of HSIL material, somatic mutations were observed in 4/5 cases, 18 different somatic driver mutations of the NRAS, EGFR, BRAF, KRAS, IDH2 oncogenes and TP53 suppressor genes were found and almost no CNA-Copy Number Aberration was identified. HSIL malignization is associated with the appearance of secondary driver mutations in oncogenes and tumor suppressor genes and a large number of structural and numerical CNA, the frequency of which correlates with the time of dysplasia malignization into cancer with a very high correlation coefficient r = 0.98, P = 0.004. The trees of dysplasia evolution into tumor were constructed for each patient.

CONCLUSION

According to the results of the work, it is assumed that the initiation of the development of mucosa dysplastic changes is due to primary driver mutations. The formation of secondary driver mutations and CNA are genetic mechanisms of malignant transformation, while the scenarios of the evolution of dysplasia into a tumor are individual and very diverse.

Thin variant of high-grade squamous intraepithelial lesion - relationship with high-risk and possibly carcinogenic human papilloma virus subtypes and somatic cancer gene mutations

AIM

To further characterise the thin variant of high-grade squamous intraepithelial lesions (HSILs) of the cervix defined by the World Health Organization as full-thickness HSILs with nine or fewer cell layers.

METHODS AND RESULTS

We examined 31 excisional cervical specimens featuring exclusively p16^INK4a -overexpressing thin HSILs with respect to size, location at the squamocolumnar junction or endocervical mucosa, human papilloma virus (HPV) subtypes (pretherapeutic clinical HPV tests and HPV genotyping on lesional tissue after excision), and somatic mutations in 50 cancer genes. Thin HSILs were typically solitary lesions, located at the squamocolumnar junction (20/31; 65%), in the endocervical columnar epithelium (6/31; 19%), and in both locations (5/31; 16%). The horizontal extension of thin HSILs ranged from 100 µm to 8 mm, with 30% being <1 mm. HPV data were available for 27 specimens. Twenty of 27 (74%) thin HSILs showed high-risk HPV subtypes: HPV16 (n = 8), HPV16 with coinfection (n = 2), HPV18 (n = 1), HPV31 (n = 1), HPV33 (n = 2), HPV52/58 (n = 2), and 'other' high-risk HPV genotypes (n = 4). Five of 27 (19%) thin HSILs showed possibly carcinogenic subtypes: HPV53 (n = 3), HPV73 (n = 1), and HPV82 (n = 1). One thin HSIL was induced by low-risk HPV6 and one by the unclassified subtype HPV44. Somatic gene mutations were not identified.

CONCLUSION

Thin HSILs were typically small lesions without somatic gene mutations. Two-thirds of thin HSILs developed after a transforming infection with high-risk HPV subtypes, and one-third were induced by non-high-risk HPV subtypes. If cervical cancer screening relies solely on presently available clinical HPV DNA tests, a significant percentage of women with HSIL will be missed.