Patients with cancer in developing countries face considerable challenges in obtaining access to care due to a lack of human resources and infrastructure. This is particularly pressing for vulnerable populations such as older adults. In this setting, many patients receiving chemotherapy are unable to report the presence of toxicities, and adverse events can go unnoticed for considerable amounts of time. The goal of this study is to assess the accuracy of an objective patient-centered measure of physical function (the number of steps taken per day measured using an accelerometer-equipped smartphone) for the remote detection of chemotherapy toxicity in older adults. This study builds on a pilot trial showing that monitoring older patients remotely utilizing an accelerometer-equipped smartphone is feasible and acceptable, and that a decline in the number of steps detected using the device can be an early sign of chemotherapy toxicity. The hypothesis of this study is that a decline in the number daily steps from a prechemotherapy baseline, measured using an accelerometer-equipped smartphone, will be accurate for detecting chemotherapy toxicity in older adults with cancer. This study will evaluate the ability of a patient-centered measure (a decline in the number of daily steps compared with a pre-chemotherapy baseline) to identify the presence of clinically-significant chemotherapy-related toxicity in Mexican older adults with cancer starting first line chemotherapy. Patients will be provided with an accelerometer-equipped smartphone with an installed pedometer application. Baseline steps per day will be obtained and recorded before starting chemotherapy. The patients' steps will be monitored daily for the first three chemotherapy cycles and compared with baseline recordings. Patients will be contacted daily and chemotherapy toxicity will be assessed by a physician. If significant toxicities are identified, the patient will be prompted to seek medical attention. The optimal cutoff point for detecting chemotherapy toxicity utilizing a decline in the number of daily steps will be chosen and validated. The adherence and satisfaction with the intervention will also be evaluated. This study could improve current methods and transform the way in which cancer care is delivered by demonstrating that a simple patient-centered measure obtained using a commercially available smartphone can aid in the accurate identification of clinically significant toxicities among a vulnerable population such as older adults with cancer.

Inclusion Criteria:

• ≥65 years old
• Any solid tumor
• Starting first-line chemotherapy
• Adjuvant, metastatic or recurrent setting
• Any socioeconomic and educational level

Exclusion Criteria:

• Patients with walking disability
• Bedridden patients (ECOG 3)
• Second or subsequent line of chemotherapy
• Inpatients
• Patients receiving radiation concomitantly with chemotherapy