false negative: an erroneous negative test result; for example, an imaging test that fails to show the presence of a cancer tumor later found by biopsy to be present in the patient is said to have returned a false negative result
fast echo spin (FSE): in MRI, echo sequence is characterized by a series of rapidly applied 180° rephasing pulses and multiple echoes
ferritin: an iron-containing protein complex, found principally in the intestinal mucosa, spleen and liver that functions as the primary form of iron storage in the body
flare reaction: the transient increase in serum testosterone for the first few weeks after starting an LHRH agonist. This increase in testosterone can potentially worsen the signs and symptoms of disease, especially in those patients with vertebral metastases and/or urinary obstruction; may be prevented by taking an antiandrogen (Casodex® or Eulexin®) several days before starting an LHRH agonist or by the use of an LHRH antagonist such as abarelix (Plenaxis®). See our paper Clinical Flare: A Crisis That Can Be Avoided.
fluoroscope: a device consisting of a fluorescent screen, used in conjunction with an X-ray tube, that shows the images of objects between the tube and the screen
flutamide (Eulexin®): an antiandrogen used in the palliative hormonal treatment of advanced prostate cancer and in the adjuvant and neoadjuvant hormonal treatment of earlier stages of prostate cancer; normal dosage is 2 capsules three times a day
focus: pl. foci: Group of (frequently neoplastic ) cells, identifiable by distinctive distribution or structure.
follicle stimulating hormone (FSH): in the male, stimulates the Sertoli cells of the testicle to make sperm
fraction: The portion of a fractionated radiation treatment that is delivered in a single session
free PSA: PSA molecules in the blood stream that are not "bound" to other proteins
free PSA %: reports the percentage of free-PSA and usually expressed as a percentage based on free PSA divided by total PSA x 100; one study showed that men with free PSA % > 25% had low risk of PC while those with < 10% free PSA % were more likely to have PC.
free radical: An atom or group of atoms that has at least one unpaired electron and is therefore unstable and highly reactive. In animal tissues, free radicals can damage cells and are believed to accelerate the progression of cancer, cardiovascular disease, and age-related diseases
frozen section: a technique in which removed tissue is frozen, cut into thin slices, and stained for microscopic examination; a pathologist can rapidly complete a frozen section analysis, and for this reason, it is commonly used during surgery to quickly provide the surgeon with vital information such as a preliminary pathologic opinion of the presence or absence of prostate cancer (usually in the pelvic lymph nodes)
FSH: See follicle stimulating hormone
fusion: combining two or more inputs of data so that they can be overlaid one upon another to provide a sense of agreement or concordance; fusion imaging studies such as ProstaScint-CT-PET are examples