As more people diagnosed with cancer are living for longer, it’s important to consider the impact of diagnosis and treatment on quality of life. One part of this is physical activity, which has been shown to improve outcomes for people living with cancer.

There is not much evidence on how physical activity changes after a cancer diagnosis. Measuring physical activity before diagnosis is hard, as it often relies on people remembering what exercise they were doing before they were diagnosed.

To tackle this, one study in Japan linked step count data already collected on smartphones with medical records to look at how cancer diagnosis and treatment affected physical activity.

How were smartphones used in the study?

Daily step counts were measured using a free smartphone app. These step counts were then linked to medical records, covering the 6 months before and 12 months after cancer diagnosis.

What did the study find?

The study included 326 people with malignant solid tumours and 1,388 people newly diagnosed with diabetes, who acted as a comparison group.

On average, people walked around 10% fewer steps in the first month after diagnosis compared with the month before diagnosis. They walked around 12% fewer steps at three months, and 7% fewer steps at 12 months, meaning they did not return to their pre-diagnosis levels. This pattern was different from people diagnosed with diabetes, whose step counts didn’t change significantly in the same period.

The size of the drop in steps also depended on the treatment people had. People who had laparoscopic (keyhole) surgery did 14% fewer steps three months after diagnosis, but were back to their baseline levels at 12 months. In contrast, people who had open surgery in the upper abdomen (nonendoscopic subdiaphragmatic surgery) did 34% fewer steps at three months and 18% fewer steps at 12 months, meaning they didn’t return to their pre-surgery levels.

Why does this matter?

Understanding how physical activity changes after diagnosis and treatment could help tailor exercise advice to improve outcomes, including quality of life. The differences in step count after different types of surgery may reflect recovery time, but they may also be linked to cancer stage, as people needing open surgery may have more advanced disease. This study shows the value of linking step count data already collected on people’s devices with medical records to answer questions that were previously difficult to study.

Read the paper: Changes in physical activity across cancer diagnosis and treatment based on smartphone step count data linked to a Japanese claims database: retrospective cohort study

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