PAPseek - Screening for endometrial and ovarian cancers

1. PapSEEK
- Screening for endometrial and ovarian
cancers
JOURNAL CLUB
16/1/2019
BY DR WINNIE CRISTAL DAUD

2. INTRODUCTION
 Endometrial and ovarian cancer account for about 25000 death each year
 3rd leading cause of cancer related mortality in women in US
 Mostly caused by high-grade tumour subtypes, which tend to metastasize before
the onset of symptoms
 Most common diagnostic test is measuring ET with TVS
 Inability to distinguish between benign and malignancy lesions, subjecting women
without cancer for unnecessary invasive procedures and their associated
complications
 High false positive rate
 As few as 1 in 50 women who tested POSITIVE from TVS was proven to be endometrial
cancer after undergoing additional diagnostic procedures

3.  Endometrial cancer - most common gynaecological malignancy
 Ovarian cancer – 2nd most common gynaecologic malignancy in US & Europe
 Often diagnosed late stage, 5 years survival rate is < 30%
 High-grade serous carcinomas (HGSCs) accounts for 90% of all ovarian cancer
deaths
 Increasing evidence suggests that most HGSCs arise in the fallopian tubes and
implant on ovarian surface
 Recent prospective study of symptomatic women reported most early diagnosed
HGSCs have extraovarian origins
 May explain the low sensitivity of TVS for early disease
 Multimodal screening with CA 125 improves sensitivity but lack specificity as CA
125 is elevated in variety of common benign condition

4.  Cancer driver genes mutation are causative agents
 It has been shown that tumour DNA could be detect in the vaginal tract of
women with ovarian cancer
 Recent proof –of-principle study showed that endometrial & ovarian
cancers shed cells that collect at the cervix, allowing detectable amount of
tumour DNA to be found in the fluids obtained during routine Pap Tests

5. PapSEEK
 Detection of endometrial and ovarian cancers based on genetic analyses
of DNA recovered from the fluid obtained during routine Pap smear
 Incorporates assays from mutations in 18 genes + assay for aneuploidy
 Use DNA from the fluid (used for pap brush) in a PCR-based, multiplex test
to assess genetic alterations that commonly occur in endometrial and
ovarian cancers
 Pap brush vs. Tao brush
 Plasma ctDNA

6.  Even a sample does not contain genetic alteration in 1 of the 18 genes
assessed, might still be aneuploidy and detected by PapSEEK
 81% (95% CI, 77 to 85%) of the Pap brush samples from women with
endometrial cancers were PapSEEK-positive
 including 78% of patients with early-stage disease and 92% of patients with
late-stage disease
 33% (95% CI, 27 to 39%) of the Pap brush samples from women with
ovarian cancers were PapSEEK-positive
 including 34% of patients with early-stage disease and 33% of patients with
late-stage disease
 Only 1.4% of the Pap brush samples from 714 women without cancer
were PapSEEK-positive, yielding a specificity of ~99%

7. Driver Gene Mutations
 Using a PCR-based error-reduction technology, Safe-Sequencing System (Safe-
SeqS) to identify mutations in the samples
 Commonly mutated genes
Endometrial Ovarian
PTEN (64%)
TP53 (41%)
PIK3CA (31%)
PIK3R1 (29%)
CTNNB1 (21%)
KRAS (18%)
FGFR2 (11%)
POLE (9%)
APC (9%)
FBXW7 (8%)
RNF43 (7%)
PPP2R1A (5%)
TP53 (74%)

8. Aneuploidy
 Using PCR-based method to amplify ~38,000 loci of long interspersed
nucleotide elements (LINEs) with a single primer pair
 LINEs have spread throughout the genome via retrotransposition and are
found on all 39 nonacrocentric autosomal arms
 After sequencing, the data are processed to identify gains or losses on
single chromosome arms

9. Pap brush
- Driver Gene
 Endometrial cancer – sensitivity 81%
 including 78% of patients with early-stage disease (Stage I & II)
 89% late stage disease (Stage III & IV)
 Ovarian cancer – Sensitivity 29%
 including 28% of patients with early-stage disease
 30% late stage disease
 Specificity ~99%
 93% contained at least 1 driver gene

10. Pap Brush
- Aneuploidy
 Endometrial cancer – sensitivity 38%
 34% early stage disease
 51% late stage disease
 Ovarian cancer – sensitivity 11%
 15% early stage disease
 9.3% late stage disease
 Specifivity ~100% (1 sample POSITIVE in 714 women without cancer)
 Most commonly altered arm
 4p, 7q, 8q, and 9q

11. Tao Brush
- PapSEEK
 Intrauterine sampling
 Increased the detection of malignancy over endocervical sampling with a Pap brush
 Endometrial cancer – sensitivity 93%
 90% early stage disease
 98% late stage disease
 Cervical cancer – 45%
 Specificity 100% (0% out of 125 women without cancer tested POSITIVE)

12. Tao Brush VS. Pap Brush
PapSEEK POSITIVE
Tao Brush Pap Brush
Endometrial cancer 91% 82%
Ovarian Cancer 45% 17%

14. Plasma Circulating Tumour DNA
 83 ovarian cancer patients (donated samples for Tao and Pap brush)
 Sensitivity 43% (detectable ctDNA)
 Sensitivity higher in patients with late stage tumours than early stage tumours
patients
 40% POSITIVE by PapSEEK
 Plasma + Pap brush – sensitivity increased to 63% for ovarian cancer
 54% early stage disease
 75% late stage disease
 Specificity 100% (0% from 192 healthy samples)

16. = 311
~
81%
= 81
~ 33%
= 114
~ 93%
= 23
~ 45%
= 52
~ 63%

17. Conclusion
 Minimally invasive and conveniently obtained during routine office visit
 Most endometrial cancer could be detected with PapSEEK
 A substantial fraction of ovarian cancer could be detected with PapSEEK
 Specificity of PapSEEK is high
 ctDNA in plasma could be used in conjunction with PapSEEK (Pap brush), increased the
sensitivity of detecting ovarian cancer to 63%
 Cost would be more than the cost of Pap Test but comparable to colonoscopy,
mammography and CT imaging
 It is a retrospective rather than prospective study. A prospective, unbioased cohort
would be more appropriate
 Would include patients with benign as well as malignant tumours

18. THANK YOU