PhD / Research · Oncology and Tumor Biology

Drug resistance

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Drug resistance — on-site reading

An introductory overview for this topic. The article introduction is reproduced here, so you do not need to leave MedAtlas to read it. It may not match the latest official medical guidance.

Drug resistance is the reduction in effectiveness of a medication such as an antimicrobial or an antineoplastic in treating a disease or condition. The term is used in the context of resistance that pathogens or cancers have "acquired", that is, resistance has evolved. Antimicrobial resistance (AMR) and antineoplastic resistance challenge clinical care and drive research. When an organism is resistant to more than one drug, it is said to be multidrug-resistant.
The development of antibiotic resistance in particular stems from the drugs targeting only specific bacterial molecules (almost always proteins). Because the drug is so specific, any mutation in these molecules will interfere with or negate its destructive effect, resulting in antibiotic resistance. Furthermore, there is mounting concern over the abuse of antibiotics in the farming of livestock, which in the European Union alone accounts for three times the volume dispensed to humans – leading to development of super-resistant bacteria.
Bacteria are capable of not only altering the enzyme targeted by antibiotics, but also, by the use of enzymes, modifying the antibiotic itself and thus neutralizing it. Examples of target-altering pathogens are Staphylococcus aureus, vancomycin-resistant enterococci and macrolide-resistant Streptococcus, while examples of antibiotic-modifying microbes are Pseudomonas aeruginosa and aminoglycoside-resistant Acinetobacter baumannii.
In short, the lack of concerted effort by governments and the pharmaceutical industry, together with the innate capacity of microbes to develop resistance at a rate that outpaces development of new drugs, suggests that existing strategies for developing viable, long-term anti-microbial therapies are ultimately doomed to failure. Without alternative strategies, the acquisition of drug resistance by pathogenic microorganisms looms as possibly one of the most significant public health threats facing humanity in the 21st century. Some of the best alternative sources to reduce the chance of antibiotic resistance are probiotics, prebiotics, dietary fibers, enzymes, organic acids, phytogenics.
Escherichia coli, S. aureus, Klebsiella pneumoniae, Streptococcus pneumoniae, A. baumannii, and P. aeruginosa were the six main causes (73%) of AMR-associated mortality in 2019, according to the 2022 Global Burden of Disease research. AMR not only causes death and disability, but it also has high financial expenses. AMR may lead to US$ 1 trillion in higher healthcare expenses by 2050 and US$ 1 trillion to US$ 3.4 trillion in annual GDP losses by 2030, according to World Bank estimations.

How this connects to Oncology and Tumor Biology

Cancer biology involves abnormal clonal growth, tissue invasion and interactions with immune, stromal and vascular components. Tumor type, grade, stage and molecular findings answer different questions; diagnostic and treatment decisions require tissue-specific evidence and multidisciplinary clinical assessment.

Text credit: Wikipedia contributors, “Drug resistance”, original article · authors & revision history · CC BY-SA 4.0. Unmodified opening extract, accessed 24 September 2026. This Wikipedia-derived section is provided under CC BY-SA 4.0; the independent MedAtlas notes and design are separate works.

On-site diagram

Drug resistance · visual study map

Scalable vector illustration. Labeled conceptual map, not a precise anatomical, histological or diagnostic image.
TOPIC LEARNING MAP · NOT AN ANATOMICAL PLATE01 · BackgroundDrug resistance is the reduction ineffectiveness of a medication such as anantimicrobial or an…02 · Main conceptThe term is used in the context ofresistance that pathogens or cancershave "acquired", that is, resistance…03 · Related processAntimicrobial resistance (AMR) andantineoplastic resistance challengeclinical care and drive research.04 · Study connectionWhen an organism is resistant to morethan one drug, it is said to bemultidrug-resistant.Drug resistanceRead the full text below the visual · all reading is on this website

The wording in this learning map is adapted from the attributed Wikipedia background section below (CC BY-SA 4.0).

Study foundation 01

What the underlying subject studies

Biomedical research begins with a focused, ethically valid question. Define the study population, variables, measurements and decision-relevant uncertainty before selecting a method.

Study foundation 02

How mechanisms and evidence connect

Compare alternative study designs and account for sampling, confounding, bias, imprecision, missing data and the limits of causal inference. Sound statistical analysis cannot repair invalid measurements or unethical recruitment.

Study foundation 03

How to develop a sound explanation

Doctoral-level mastery involves reading primary methods, reproducing calculations, writing transparent protocols and defending the assumptions behind each conclusion. University-specific courses and laboratory competencies differ.

References and verification (optional)

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