The BTP (Breakthrough pain)was defined as "a transient exacerbation of pain that occurs either spontaneously, or in relation to a specific predictable or unpredictable trigger, despite relatively stable and adequately controlled background pain".

The BTP is a common clinical features in patients with cancer pain (BTcP: breakthrough cancer pain). The prevalence of BTcP is equal to 56%.

Currently, the investigators tend to recognize the idiopathic/spontaneous or accident BTcP in the three sub-types: voluntary, non- voluntary and procedural.

The diagnosis of BTCP is not always easy because in the cancer patient is normal to observe changes in the intensity of pain during the day, so it is necessary to differentiate slight fluctuations from the presence of real episodes of BTCP, for which is necessary to use a rescue treatment adjusted. In the study will be proposed the use of a diagnostic algorithm, present in the literature, to perform the diagnosis of BTCP.

In the presence of BTCP, is important both a correct controlled background pain with major opioids, which can reduce the number and the intensity of the painful episodes, both implement an adjunctive therapy, called "rescue", to be administered at the time which takes over the painful episode using, in this case, an opioid greater.

Inclusion Criteria:

• diagnosis (histologic or cytologic) of locally advanced cancer and / or metastatic disease;
• presence of baseline pain of moderate intensity / severe, necessitating treatment with opioids of the 3rd step / WHO, already in progress or to be undertaken at a stage just prior to the start of the study (see also criterion 4 where indicates that "the pain of base must be adequately controlled with opioids of the wHO 3rd step");
• estimated life expectancy of more than one month;
• presence of BTCP, diagnosed according to the criteria set by the definition of BTCP and the algorithm of Davies, for which it is established to undertake a treatment "rescue" of painful episodes, with the appropriate opioid drugs at the time of commencement of the study;
• capable of taking opioid medications for pain basic and breakthrough pain, by any route of administration;
• aged more than 18 years.

Exclusion Criteria:

• participation in other research projects that are in conflict or could confound the results of the study;
• absence of informed consent, or withdrawal of consent for study participation;
• presence of some pathological mental or psychiatric conditions, due to the tumor or concomitant diseases, which interfere with the state of consciousness or the ability to judge the point of jeopardizing the study protocol;
• need treatment for comorbid conditions present at the beginning of the study that could create potentially dangerous drug interactions with opioids (conazolici use of antifungals or macrolide antibiotics);
• contraindications of any kind for use of opioid drugs;
• positivity of a story, past or current, of substance abuse;
• inability to ensure regular follow-up;
• diagnosis of primary tumor of the brain;
• situation of the presence of BTCP already in treatment with opioid rescue of 3rd step;
• decision to use drugs "rescue" of different opioid 3rd step / WHO (NSAIDs, opioids of 2 ° step), for the treatment of BTCP;
• diagnosis of chronic renal failure proclaimed already in place, with values of blood creatinine ≥ 2 mg / dL.

This study involves a longitudinal evaluation of BTCP in cancer patients with pain, through a follow-up of 4 weeks, which will examine in a dynamic clinical aspects (variation over time of the number and duration of episodes, painful intensity, changes in ATC and rescue therapy).