Ozone Treatment in Paresthesia (Numbness, Tingling) Secondary to Chemotherapy-induced Peripheral Neuropathy

The goal of this phase II/III randomized clinical trial is to evaluate the effect of adding rectal ozone therapy to the usual management of patients with paresthesia (numbness and/or tingling) due to chemotherapy-induced peripheral neuropathy (CIPN). Ozone treatment consists of the rectal insufflation of 180 - 300 milliliters of an ozone/oxygen gas mixture.

The main questions to answer are:

1. Can ozone therapy improve patients' self-perceived level of numbness and tingling? 2. Can ozone therapy improve patients' self-perceived health-related quality of life (HRQoL)?

In 42 patients with chronic numbness and tingling secondary to chemotherapy, the researchers will compare:

* the addition of rectal ozone insufflations * versus the addition of rectal oxygen insufflations (placebo). Participants will receive 40 rectal gas (ozone versus oxygen) insufflations in 16 weeks and will continue other symptomatic or cancer treatments prescribed by their oncologists.

Before treatment, after treatment, and 12 weeks after treatment, they will be evaluated:

* Several questionnaires about neuropathy, quality of life, and anxiety and depression. * Biochemical parameters of oxidative stress and inflammation * Hyperspectral images of hands and feet * Toxicity of procedure.