The primary objective of this prospective pilot study is to examine the variation of cognitive function at various time-points in stage I-III breast cancer patients who have undergone or are undergoing adjuvant systemic therapy (chemotherapy and/or anti-hormonal therapy) and compare this to a group of healthy controls to evaluate if there is a difference. All randomized patients and their respective controls would be required to complete the computerized neuropsychological assessment CANTAB at certain time-points.These patients and controls would also be given on the same day as CANTAB testing, a set of questionnaires to evaluate subjective factors such as anxiety, depression, fatigue or menopausal symptoms which may also have an effect on cognition. Subjective assessment of cognitive function will rely on self-reporting by study participants using a validated questionnaire.The potential risks to subjects are minimal, as this is a study without any intervention regarding the medical management of patients. By participating in this study, subjects will be helping in the aim of determining if there is cognitive impairment post-therapy, and if so, how prevalent is this phenomenon, when it arises and how it changes with time. This will consequentially play an important role with regard to patient knowledge. Furthermore, if chemotherapy is shown to be associated with cognitive impairment, further studies can be carried out to determine the exact pathophysiology behind this phenomenon. This will allow for sensitive and timely detection of cognitive dysfunction in patients who have received chemotherapy and/or anti-hormonal therapy, and subsequently open the avenue for research in preventing or alleviating this phenomenon. This is crucial in improving patients' quality of life, social and occupational performance.

The investigators hypothesis is that systemic adjuvant therapy in the form of chemotherapy and/or anti-hormonal therapy given to primary breast cancer patients can cause cognitive impairment.

Inclusion Criteria:

1. Histologically confirmed stage I-III breast carcinoma
2. < 65 years old
3. Female

Exclusion Criteria:

1. Previous exposure to chemotherapy/anti-hormonal therapy for any other malignancy
2. Previous neoadjuvant therapy for breast cancer
3. Concomitant second primary in-situ or invasive carcinoma or previous history of carcinoma/carcinoma-in-situ
4. Known disease or injury to the central nervous system (including neurodegenerative diseases, epilepsy), severe visual or auditory disorders
5. Motor weakness due to any cause which makes using a touchscreen computer difficult
6. Known background of depression, anxiety disorders or other neurobehavioural conditions
7. Ongoing use of tranquilisers or anti-depressants
8. Previous neuropsychological testing
9. Current or previous history of alcohol or drug dependent

Patients being treated with breast cancer at National University Hospital (Singapore)and healthy women would be used consisting of a friend or relative of the patient.