Approximately 95% of female patients present with non-metastatic breast cancer, without macroscopic metastatic disease [1] [][][]. In patients with primary (non-metastatic) breast cancer, the risk of metastatic relapse is greatest within 2 years after primary surgery [2] and it is estimated that most of recurrences are diagnosed > 5 years after surgery [3]. Researchers have identified the critical role of perioperative period on survival outcomes of patients with cancer. Postoperative inflammation along with elevated catecholamine levels, immunosuppression, pro-angiogenesis state, and the release of tumour cells into the circulation during and after surgery were proposed as possible mechanisms for cancer progression [4]. The standard methods for surveillance and detection of breast cancer recurrence, include clinical examination and annual mammogram [5]. However, improved surveillance methods to determine risk of recurrence after primary breast cancer surgery are highly desirable [6]. Accurate blood based biomarkers that could identify microscopic residual disease (MRD) postoperatively could aid in detection of patients at higher versus lower risk for recurrence and could potentially spare patients of neo/adjuvant therapies that are not needed [7].

Genomic analysis of circulating blood-based biomarkers as ctDNA known as liquid biopsies provides insights into the dynamic molecular profile of the solid tumour in readily accessible and non-invasive way [8]. The nucleic acids including DNA which is secreted from the tumour microenvironment, contains somatic mutations unique to cancer cells that can be detected systemically in body fluids including blood [9]. Since the half-life of ctDNA is short, it may reflect the tumour burden of the patients in a real-time [10] and correlates with tumour progression [[11], [12]] [12].

Phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) is an oncogene that encodes the p110 element of PI3 kinase [13,14]. Evidence has suggested that PIK3CA gene mutations is prevalent in 30–40% of all breast cancers, with a higher prevalence (45%) observed in estrogen receptor/progesterone receptor (ER/PR) positive and HER2 positive breast cancers. In breast cancer, PIK3CA gene mutations is commonly detected on two “hotspot" regions exons 9 and 20 that account for 80–90% of all PIK3CA mutations [[15], [16], [17]]. PIK3CA gene mutations in tumour tissue as well as ctDNA had been identified in patients with advance breast cancers and associated with survival in breast cancer [1,8]. In SOLAR-1 trial, researchers discovered that treatment with alpelisib–fulvestrant prolonged progression-free survival among patients with PIK3CA-mutated, HR-positive, HER2-negative advanced breast cancer [19] [][][]. Recently, researchers have identified the feasibility of detecting PIK3CA gene mutations in ctDNA in patients with early-stage breast cancer patients in preop period and 3–5 week post op period [20] [][][].

In recent times, oncological research has largely explored the potential effects of the perioperative period as one of the contributing factors for recurrence in breast cancer. Therefore, this study investigated the feasibility of detecting PIK3CA gene mutation in ctDNA during the preoperative and postoperative periods, in patients with non-metastatic breast cancer and correlated the findings with prognosis in patients with breast cancer.