"Cancer is a serious disease."

[I.Schmidt1]

όγκος is cancer?

[spdl79]

A native speaker might want to correct me, but I understand όγκος as (amongst other things) 'tumour'. So although someone with cancer will have tumour(s), they're not exactly the same things - όγκος is a symptom of καρκίνος. Like... how having a cough is a symptom of having the flu. Hope that helps!

[Dimitra956826]

As a native, I think you are quite correct! ^.^

[YanisOdyss]

Όγκος is tumor

[thoas]

Shouldn't νόσος also be accepted?

[G.Georgopoulos]

"Νόσος" has been added, thank you! I'm going to add "νόσημα" as well. I'd like to elaborate on these terms a bit.

"Αρρώστια" is an everyday word for "disease". "Ασθένεια" is also an everyday, yet better-sounding, synonym and is sometimes used in medical terminology. The two scientific terms are "νόσος" and "νόσημα". These terms are often used interchangeably, but that's not always the case. For anyone who might be interested, I'm giving a few usage examples below:

Infectious disease=Λοιμώδης νόσος=Λοιμώδες νόσημα

Gastrointestinal tract disorders=Διαταραχές (=disorders) του γαστρεντερικού συστήματος=Νοσήματα (=diseases) του γαστρεντερικού συστήματος.

Rheumatic diseases=Ρευματικά νοσήματα

Chronic disease: Χρόνια νόσος=Χρόνιο νόσημα

"Νόσος" is also often used in eponymous diseases (=diseases named after scientists), for example:

Alzheimer's disease: Νόσος Αλτσχάιμερ/Alzheimer

Parkinson's disease: Νόσος Πάρκινσον/Parkinson

"Νόσος" and "νόσημα" can be used instead of the word "ασθένεια", but not vice versa.

[thoas]

Thanks for the detailed explanation!