Medical Oncology Glossary
100 terms total — 24 showing — Last updated 15 Sep 2026
Ki-67 index
A measure of cellular proliferation expressed as the percentage of Ki-67 positive tumor cells, used in cancer prognosis and treatment decisions.
partial response
Tumor response category indicating significant reduction in tumor burden but not complete disappearance.
pathologic complete response
Complete absence of invasive tumor cells in surgical specimens after preoperative treatment, indicating excellent treatm...
PD-L1
Programmed death-ligand 1; a protein expressed on tumor cells that suppresses immune responses and serves as a predictiv...
Performance Status
Standardized assessment of a patient's functional ability and daily activity level.
PET-CT
Combined positron emission tomography and computed tomography imaging used for cancer staging and response assessment.
pleural effusion
Abnormal accumulation of fluid in the pleural space, often malignant in oncology patients.
pneumonitis
Lung inflammation adverse event commonly associated with cancer immunotherapy.
progression-free survival
Time from treatment start until disease progression or death from any cause.
progressive disease
Tumor response category indicating cancer growth or spread despite treatment.
protocol deviation
Departure from approved clinical trial procedures that may affect safety or data integrity.
pseudoprogression
Apparent tumor progression on imaging that actually represents inflammation or treatment effect rather than true disease...
radiosensitivity
Degree to which cells or tissues are susceptible to damage from ionizing radiation exposure.
RECIST criteria
Standardized guidelines for evaluating tumor response to treatment in clinical trials.
refractory
Cancer that does not respond to treatment or becomes resistant to therapy.
salvage therapy
Treatment given when cancer returns or fails to respond to initial therapy.
sanctuary site
Anatomical locations where systemic therapies have limited penetration, potentially harboring residual cancer cells.
sarcoma
A type of cancer that develops in connective tissues such as bone, muscle, fat, or blood vessels.
stable disease
Tumor response category indicating neither significant shrinkage nor growth of cancer lesions.
staging
Process of determining the extent and spread of cancer in the body.
therapeutic index
The ratio between a drug's effective dose and its toxic dose, indicating the safety margin of cancer treatments.
thrombocytopenia
Abnormally low platelet count that increases bleeding risk during cancer treatment.
tumor debulking
Surgical removal of as much tumor tissue as possible when complete resection cannot be achieved.
tumor heterogeneity
The existence of distinct subpopulations of cancer cells within the same tumor, affecting treatment response and disease...
tumor lysis syndrome
Potentially fatal metabolic complication from rapid breakdown of cancer cells during treatment.