Breast cancer is the most common type of cancer among women worldwide. The incidence rate has reached approximately 16%. According to 2016 data from the Ministry of Health, the incidence of breast cancer in Turkey is 46.8 per 100,000 people and approximately 17,000 women are diagnosed with breast cancer each year. While breast cancer survival rate is 80% in developed countries, this rate varies between 40-60% in low-middle income countries. Survival can be increased with early diagnosis and more effective treatment methods. However, a wide range of treatment-related complications are observed during and/or after breast cancer treatment. Cancer survivors are exposed to a variety of direct (local/regional therapy, systemic therapy and supportive care) and indirect factors (modifiable and non-modifiable risk factors) that can have adverse effects on pulmonary, cardiovascular, hematologic and musculoskeletal components. Oxygen consumption in cancer patients may be adversely affected by aging, deconditioning, existing comorbidities, cancer pathophysiology and cancer treatments (surgery, radiation, chemotherapy and hormone therapy). Although decreased functional capacity is common after breast cancer treatment, there are few studies evaluating maximal arm exercise capacity with oxygen consumption.

In recent years, thanks to the increasing treatment possibilities with the developing technology, the majority of patients show good functional recovery after breast cancer. However, it has been reported that the treatments negatively affect the functional capacity of the upper extremities, daily life, work and social activities and reduce the quality of life. It has also been reported that breast cancer-related lymphedema (BCRL) may both cause and exacerbate treatment-related complications such as decreased functional capacity of the upper extremities and worsened quality of life after breast cancer treatments. In addition, it has been found that lymphedema decreases the muscle strength and range of motion of the limb in which it develops and causes an increase in symptoms such as pain, fatigue and discomfort. These complications caused by lymphedema lead to decreased functional level of the upper extremity, activity limitations and decreased quality of life. Cardiovascular health is negatively affected after breast cancer. Decreased cardiorespiratory performance also has direct consequences on daily task performance and therefore quality of life is negatively affected.

The gold standard method of measuring cardiorespiratory exercise capacity is cardiopulmonary exercise testing (CPET). This method determines the causes of limitation during exercise and gives maximal oxygen consumption (VO2max) as a measure of maximum performance. In cancer patients, the oxygen system may be adversely affected by chemotherapy. Effects of chemotherapeutic agents on respiratory, cardiac, blood, vascular or skeletal muscle functions have been observed, potentially contributing to impaired cardiorespiratory fitness. Cardiorespiratory function is not routinely measured at any stage of breast cancer treatment and CPET is rarely used in clinical settings. Although low VO2max measurements have been observed in intervention studies during breast cancer survivorship and these studies were conducted without the use of an arm ergometer, to our knowledge, there is very limited information on the impact of cancer treatment on cardiorespiratory fitness using gold standard testing methods.

Although decreased functional capacity is common after breast cancer treatment, there are few studies evaluating maximal arm exercise capacity with oxygen consumption.

Inclusion Criteria:

Breast Cancer Group:

1. Being between 18-65 years of age,
2. Volunteering to participate in the research,
3. Stage I-III breast cancer,
4. At least 15 months after breast cancer surgery,
5. Six months after active breast cancer treatment (i.e. surgery/chemotherapy),
6. No lymphedema
7. No problems in reading and/or understanding the scales and being able to cooperate with the tests,

Healthy group:

1. Age between 18-65 years,
2. Volunteering to participate in the research,
3. No problems in reading and/or understanding the scales and being able to cooperate with the tests.

Exclusion Criteria:

Breast Cancer Group:

1. Presence of active infection,
2. Musculoskeletal and neurological diseases that may affect exercise performance, symptomatic heart disease,
3. Having a neurological disease or other clinical diagnosis that may affect cognitive status.

Healthy group:

1. Having any orthopedic or neuromuscular condition that would interfere with walking or exercise performance,
2. Having any chronic disease or psychiatric disorders or mental impairments that may interfere with cooperation or compliance with exercise tests

Patients between the ages of 18-65 years who are diagnosed with breast cancer at Hacettepe University Hospital, Department of Internal Medicine, Division of Medical Oncology, and who volunteer to participate in the study will be included in the study. For healthy groups, age and gender appropriate volunteers will be recruited for the study