Sen. John McCain received medical treatment for a minor tear to his right Achilles tendon suffered over the weekend, his office said in a statement Monday.

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Sen. John McCain received medical treatment for a minor tear to his right Achilles tendon suffered over the weekend, his office said in a statement Monday.

The 81-year-old Arizona Republican has been undergoing treatment for brain cancer ever since his diagnosis became public in July. In an interview with CBS’s “60 Minutes,” McCain said his brain cancer is “very, very serious.”

“Senator McCain was treated at Walter Reed Medical Center over the weekend for a minor tear in his right Achilles tendon, as well as for other normal and non-life-threatening side effects of cancer therapy,” the statement read. “Senator McCain has returned to work in the Senate and will be wearing a walking boot until his injured tendon is fully healed.”

This is the third in a small string of incidents that have led to Republican senators needing medical attention this fall.

Rand Paul sustained five rib fractures and lung contusions after a neighbor assaulted the senator in his home in Bowling Green, Kentucky this weekend. Both Capitol Police and the FBI are still investigating the incident.

Thad Cochran of Mississippi returned to Capitol Hill Oct. 17 after recovering from a urological issue from late September.