The aim of this study was to longitudinally assess the characteristics of background pain and breakthrough pain (BTcP), analgesic treatment, and satisfaction with treatment four weeks after the first assessment. Methods: Adult cancer patients with a diagnosis of BTcP were included. At T0, age, gender, visit setting, cancer diagnosis, the extent of the disease, ongoing anticancer treatments, and Karnofsky level were recorded. The background pain intensity in the last 24 h (on a numerical scale 0–10), opioids used for background pain, and their doses, expressed as oral morphine equivalents (OME), as well as other analgesic drugs, were recorded. The number of BTcP episodes, their intensity, predictability and precipitating factors, onset duration of untreated episodes, and interference with daily activities were collected. Analgesics and doses used for BTcP, and the mean time to meaningful pain relief after taking medication, were assessed. The level of satisfaction with BTcP medication was also assessed. Adverse effects to be attributed to these medications were also recorded. At T4, the same data were evaluated. Results: After one-month follow-up, patients had a lower number of BTcP episodes and peak intensity, possibly due to the optimization of background analgesia. The principal characteristics of BTcP did not change significantly. Conclusion: A careful and continuous assessment should be guaranteed to all patients to limit the burden induced by BTcP, other than treating BTcP episodes with short-onset opioids.