Cognitive functioning will be measured using the ASC (Amsterdam Cognition Scan) at baseline and follow-up. This will be measured before and after standard (neo)adjuvant systemic therapy. The ACS will determine the cognitive test performance through seven cognitive tests with 11 outcome measures. In this study the score differences in cognitive functioning between baseline and the two follow-up time points at 24 and 36 months after surgery will be calculated for patients treated with standard systemic therapy.

The EORTC-QLQ-OH15 will provide a detailed overview of oral health symptoms associated with cancer. The EORTC-QLQ-OH15 will be shortened to a 11-item questionnaire with a 4-point scoring scale defined by the terms: not at all, a little, quite a bit and very much.

The shortened Xerostomia Inventory will provide a detailed overview of oral health symptoms associated with cancer. The shortened Xerostomia Inventory includes 5 items with a 3-point scoring system defined by the terms: never, sometimes, always.

The Oral Impact on Daily Performance index will include 6 questions with a 6-point scoring system assessing the influence of oral health related problems on daily life functions.

The oral self-care questionnaire will provide further insights in the differences in oral care routines during follow-up. At baseline the self-care questionnaire will include 5 items compared to only 2 items at follow up.

Resource use will be measured using the Dutch hospital data (DHD). The costs of the standard of care will be estimated using data on patient's treatments from the Dutch Hospital Database (DHD). These results will be implemented in a cost-effectiveness model.

Costs will be measured using the Dutch hospital data (DHD). The costs of the standard of care will be estimated using data on patient's treatments from the Dutch Hospital Database (DHD). These results will be implemented in a cost-effectiveness model.

Resource use will be measured using iMTA Medical Consumption Questionnaire (iMCQ). It is a not disease-specific questionnaire, which includes questions related to frequently occurring contacts with health care providers.

Resource use will be measured using the iMTA Productivity Cost Questionnaire (iPCQ). The iMTA Productivity Cost Questionnaire (iPCQ) measures the impact of disease on the ability to perform work.

Number of patients alive and dead

Number of patients with recurrence of disease

The levels of ctDNA at different time points will be assessed to determine ctDNA dynamic changes during standard of care (neo)adjuvant systemic therapy and their relation to treatment outcome.