Analysis of Cervical Mutations Aids Endometrial Cancer Diagnosis

October 2, 2019
Leanne Marcello, MS

Diagnosis of endometrial carcinoma made easier by analysis of mutations in cervix or endometrial tissue.

A recent study published in the International Journal of Cancer showed that analyzing mutations either from cervical cytology or from pipelle endometrial biopsies increases the chance of catching endometrial carcinoma earlier. The study authors, Casper Reijnen, MD, et al., note that guidelines for clinical practice will follow prospective validation.

Clinical guidelines favor aspiration with a cornier pipelle for sampling of endometrial tissue via biopsy, an outpatient procedure. It is relatively reliable, quick and minimally invasive; however, a mean Visual Analogue Scale pain score of 6.5 is reported in postmenopausal women, and up to 30% of all pipelle endometrial biopsies fail to diagnose patients who have current disease. Eight percent of these diagnostic delays are caused by technical failure, while insufficient tissue volume accounts for another 22% of the failures.

Estimates are that pre-malignancies are missed in some 8% of samplings with insufficient volume of tissue retrieval. As such, second confirmatory procedures are recommended, to include either dilatation and curettage or hysteroscopic biopsy. This secondary procedure fosters additional stress on the patient, including higher costs, more time off, and additional anesthesia- or procedure-related risks. Ramifications may be amplified in women with other health issues, such as genetic predisposition, Lynch syndrome, or obesity. There is a great need for identifying additional markers that may aid in diagnosis, which was the aim of the study.

In this multicenter prospective cohort study, participating patients were either treated surgically for endometrial carcinoma or, in the control group, for a benign gynecological condition. Researchers obtained a cervicovaginal self‐sample, pap smear, pipelle endometrial biopsy, and surgical specimen of endometrial tissue. They analyzed the samples, seeking mutations in eight different genes, by employing a targeted sequencing panel. Researchers calculated specificity, sensitivity, and predictive values.

Fifty‐nine patients with endometrial carcinoma took part in the study, along with 31 cancer-free patients in the control group. With a range of 38-88 years, median age of patients with endometrial cancer was 69. Control patients ranged in age from 45-82, with a median age of 57.
Mutations identified after collection were classified as “pathogenic,” “likely pathogenic,” “mutations of unknown significance,” “likely benign,” or “benign” and the first three categories were deemed potentially pathogenic. Using the using the McNemar c2 test, sensitivity and specificity were then calculated and compared. Among all participants, diagnosis based on pipelle endometrial biopsies showed sensitivity of 79% and specificity of 100%. In patients with endometrial carcinoma, 97% of the surgical specimens revealed at least one mutation. Pap smears, self‐samples, and pipelle endometrial biopsies showed a sensitivity of 78%, 67%, and 96%, respectively, with specificities of 97%, 97%, and 94%. Pairing any one of these methods with histopathological pipelle endometrial biopsy analysis resulted in sensitivities of 96%, 93%, and 96%, respectively.

Some 70% of endometrial carcinoma cases were endometrioid endometrial carcinoma. Serous carcinoma accounted for 15%, and other non-endometrioid carcinomas made up 14%. Two percent of samples were positive for leiomyosarcoma. In control patients, 29% were diagnosed with cystadenomas, 23% with fibromas/teratomas, 29% with uterine myomas, and 19% with other benign histologies.

Because only a small percentage of DNA in the cervix is tumor DNA, mutant allele frequencies in pap and self-samples were low, requiring subsequent sequencing to detect a variant allele frequency of less than 3%. This suggests that endometrial cancers disperse neoplastic cells into
the uterus, cervical and vaginal areas. Microscopic analysis revealed neoplastic cells in 50%  of pap samples and 79% of pipelle endometrial biopsies, but  mutations were detected even in those samples without detectable neoplastic cells, perhaps due to free floating tumor DNA. This supports the proposed value of mutational analysis in early diagnosis of endometrial cancer.

"Combined with histopathological assessment, mutational analysis is a minimally invasive technique with high diagnostic accuracy and could offer an alternative approach in patients currently undergoing invasive procedures," according to the authors, led by Dr. Reijnen.