The goal of this clinical research study is to learn if fentanyl given under the skin can reduce shortness of breath in cancer patients. Researchers also want to learn if it can help to improve your physical function. In this study, fentanyl will be compared to a placebo.

Fentanyl is commonly used for treatment of cancer pain. It is believed to help patients with their shortness of breath as well.

A placebo is not a drug. It looks like the study drug but is not designed to treat any disease or illness. It is designed to be compared with a study drug to learn if the study drug has any real effect.

Study Groups:

If you are found to be eligible to take part in this study, you will be randomly assigned (as in the flip of a coin) to either receive fentanyl or placebo. You will have an equal chance of being assigned to either group.

Study Drug/Placebo Administration:

Before you receive the study drug/placebo, you will walk back and forth in an indoor corridor for up to 6 minutes. You may feel out of breath or become exhausted. You may slow down, stop, and rest at any time you need to.

After that, you will sit down and rest (for up to 1 hour). During this time, the study drug/placebo will be prepared.

You will then be given a study drug/placebo shot under the skin in your arms or legs. You will then wait for another 15 minutes and repeat the walking test.

Study Visit:

During your study visit, the study staff will collect information from your medical record about your age, sex, race, disease type, how well you are able to perform the normal activities of daily living, any drugs you are taking, and possible causes of shortness of breath.

You will also complete 2 walking tests. Before the walk tests, you will complete 2 questionnaires. One (1) of them asks about any breathing symptoms you may be having, and the other asks about any other symptoms you may be having. It should take about 10 minutes to complete these questionnaires.

Before and after each walk test, the study staff will record your heart rate, breathing rate, and the level of air breathed out using a measuring device that will be clipped onto your finger. The study staff will also ask you questions about how hard it is to catch your breath and your level of tiredness.

During each walk test, you will be asked about how hard it is to catch your breath. The distance you walked and how often and for how long you stopped will be recorded. Before and after the second walk test, the study staff will ask you about any side effects from the study drug/placebo that you may be having.

During the rest period between the 2 walk tests, you may be asked how hard it is to catch your breath several times.

At the end of the study visit, you will fill out 1 questionnaire that asks if you think the study drug/placebo is helping you, and how satisfied you are with the study. It should take about 5 minutes to complete the questionnaire.

Length of Study:

You will be on this study for up to 100 minutes.You will be taken off study if intolerable side effects occur during the study.

This is an investigational study. Fentanyl is FDA approved and commercially available for the treatment of pain. It's use to help with shortness of breath is investigational.

Up to 20 patients will be enrolled in this study. All will be enrolled at MD Anderson.

Inclusion Criteria:

1. Diagnosis of cancer
2. Breakthrough dyspnea, defined in this study as dyspnea on exertion with an average intensity level >=3/10 on the numeric rating scale
3. Outpatient or inpatient at MD Anderson Cancer Center seen by the Supportive Care or Rehabilitation Service
4. Able to communicate in English or Spanish
5. Ambulatory and able to walk with or without walking aid
6. On strong opioids with morphine equivalent daily dose of 30-580 mg, with stable (i.e. +/- 30%) regular dose over the last 24 hours
7. Karnofsky performance status >=50%
8. Age 18 or older

Exclusion Criteria:

1. Dyspnea at rest >=7/10 at the time of enrollment
2. Supplemental oxygen requirement >6 L per minute
3. Delirium (i.e. Memorial delirium rating scale >13)
4. History of unstable angina or myocardial infarction 1 month prior to study enrollment
5. Resting heart rate >120 at the time of study enrollment
6. Systolic pressure >180 mmHg or diastolic pressure >100 mmHg at the time of study enrollment
7. History of active substance abuse within the past 12 months
8. History of allergy to fentanyl
9. Unwilling to provide informed consent

Adverse effect collection from baseline up to 100 minutes for study participation.

The small sample size means findings are susceptible to random errors and regression to the mean.