Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2022

The uptake of germline and somatic BRCA mutation testing in women with high grade serous ovarian cancer in the public hospital system in South Australia  (#232)

Andry Santoso 1 , Ganessan Kichenadasse 1 , Sudarsha Selva-Nayagam 2 , Shahid Ullah 3 , Sellvakumaran Paramasivam 4 , Emily Stevens 4 , Martin Oehler 5 , John Miller 5 , Eryn Dow 2 6 , Vineet Kwatra 7
  1. Medical Oncology, Flinders Centre for Innovation in Cancer, Flinders Medical Centre, Bedford Park, SA, Australia
  2. Medical Oncology, Royal Adelaide Hospital, Adelaide, SA, Australia
  3. College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
  4. Gynaecology Oncology, Flinders Medical Centre, Bedford Park, SA, Australia
  5. Gynaecology Oncology, Royal Adelaide Hospital, Adelaide, SA, Australia
  6. Department of Adult Genetics, The Queen Elizabeth Hospital, Woodville, SA, Australia
  7. Medical Oncology, Lyell McEwin Hospital, Elizabeth Vale, SA, Australia

Aims

All women with non-mucinous epithelial ovarian cancers should be referred for genetic testing, particularly for BRCA1/2, to access targeted therapy, identify those who may benefit from risk-reducing surgery and predicting familial risks. This retrospective study aimed to determine the rate of germline and/or somatic BRCA testing in women with high-grade serous ovarian cancer. Secondary outcomes were the number of women with a germline or somatic only mutation, and to find characteristics associated with reduced testing.

Methods

All adult women with high-grade serous ovarian cancer discussed at the two South Australian gynaecology-oncology multidisciplinary meetings from January 2020 to June 2021 were included. Descriptive statistics were used for the primary outcome. Characteristics were assessed for significance using chi-square or Fisher’s exact test. Significant variables were further analysed with multivariable logistic regression.

Results

Of the 127 women included, 117 (92.1%) had germline testing, 78 (61.4%) had somatic testing and 7 (5.5%) had neither. Of the women who had germline testing, 17 (14.5%) had pathogenic variants and 1 with a germline mutation did not have a somatic mutation. Of the 103 women who were germline wild-type or were not tested, 60 (58.3%) proceeded to have somatic testing. Of the women who had somatic testing, 15 (19.2%) had pathogenic variants, 7 of which were somatic only mutations. Overall, 24 (18.9%) had either germline or somatic pathogenic variants. Women who had surgery (OR 4.32, 95% CI 1.15-16.22, p=0.03) were more likely to have germline testing. No characteristics resulted in statistically significant differences in the rates of somatic testing.

Conclusion

Quality improvement measures and a standardised approach to testing is required to improve the uptake of testing in South Australia. Both somatic and germline testing are important due to the risk of false negatives with somatic testing and the chance to have a somatic only mutation.