Molecular tests for detection of PIK3CA mutations in men and postmenopausal women with HR+/HER2–, locally advanced or metastatic breast cancer: A Health Technology Assessment
Health technology assessment|
The Norwegian Institute of Public Health was commissioned to evaluate molecular tests for the identification of somatic PIK3CA mutations in men and postmenopausal women with HR+/HER2–, advanced or metastatic breast cancer (BC).
The Norwegian Institute of Public Health was commissioned to evaluate molecular tests for the identification of somatic PIK3CA mutations in men and postmenopausal women with HR+/HER2–, advanced or metastatic breast cancer (BC). Tumours harbouring PIK3CA mutations constitute up to 36% of cases with HR+/HER2- BC, which suggests that around 48 patients may be considered for treatment with PI3k inhibitors (e.g. alpelisib) in Norway each year. Accurate and reliable detection of PIK3CA mutations is important for correctly identifying patients who may benefit from targeted treatment.
We included three original studies that reported concordance between (i) two PCR assays; (ii) two NGS-panels, and (iii) ddPCR and NGS for the detection of PIK3CA mutations. Experts were contacted for cost information. The results of this HTA show that:
- Un-pooled results (3 studies) provided inadequate evidence for test accuracy according to the EGAPP quality tool, and quality of reporting was poor.
- Single studies, with relatively small sample sizes, reported very good con-cordance between tests, which all used plasma samples(Cohen’s k: 0.80 to 0.86)
- For the detection of PIK3CA in isolation, the costs for testing using PCR is less than NGS-panel testing. However, using PCR assays for the detection of additional relevant mutations, will increase total cost. At present, the capital and infrastructure as well as maintenance costs are higher for NGS than PCR.
- Assuming that about 140 patients with metastatic BC are eligible for testing to detect of PIK3CA mutations in Norway each year, the costs were estimated to be approximately NOK 322,000.
- All tests have advantages and limitations, but due to incomplete information a proper comparison was difficult to make. The choice of a suitable test for the detection of PIK3CA mutations depends on accessibility of testing modalities, economic considerations, sample type and risk of false negatives, and turnaround time.
- Future research should focus on conducting larger cohort studies with well-defined patient populations, that follows the patients from testing (or no testing), through treatment and final outcomes. Further, robust and replicable methods, as well as a reporting standard checklist, should be used for increased clarity.