Η διάγνωση καρκίνου επιβεβαιώθηκε.

Η is the feminine singular definite article in the nominative case. In this sentence, it goes with διάγνωση because διάγνωση is a feminine singular noun and the subject of the sentence.

So:

• η διάγνωση = the diagnosis

At the start of the sentence it is capitalized as Η, but it is the same word as η.

διάγνωση is the nominative singular form, because it is the subject of the sentence: the diagnosis is the thing that was confirmed.

Greek marks grammatical roles with case, so the subject normally appears in the nominative.

Dictionary form:

• η διάγνωση = diagnosis

In this sentence:

• Η διάγνωση ... επιβεβαιώθηκε.
• literally, The diagnosis ... was confirmed.

καρκίνου is the genitive singular of ο καρκίνος (cancer).

Greek often uses the genitive where English uses of. So:

• διάγνωση καρκίνου = diagnosis of cancer

This is a very common Greek structure:

• noun + genitive noun

Examples:

• διάγνωση καρκίνου = diagnosis of cancer
• θεραπεία καρκίνου = treatment of cancer

So καρκίνου is not a different word; it is the genitive form of καρκίνος.

Greek often leaves out the article in this kind of expression, especially in formal, medical, or general wording.

So:

• διάγνωση καρκίνου = diagnosis of cancer

This sounds natural and standard.

You could also see:

• η διάγνωση του καρκίνου

That usually sounds more specific, more like the diagnosis of the cancer or the diagnosis of that cancer/case of cancer, depending on context.

So the version without the article is normal and idiomatic here.

επιβεβαιώθηκε is the aorist passive, 3rd person singular.

It means:

• was confirmed

Breakdown:

• επιβεβαιω- = confirm / be confirmed
• -θήκ- = a common passive aorist marker
• -ε = 3rd person singular ending

So the grammar is roughly:

• Η διάγνωση καρκίνου επιβεβαιώθηκε.
• The cancer diagnosis was confirmed.

This is a one-word past passive form, which is very common in Greek.

Unlike English, Greek often does not need a separate verb like was to form the passive past.

English:

• was confirmed

Greek:

• επιβεβαιώθηκε

So Greek packs the ideas of:

• past time
• passive voice
• 3rd person singular

into a single verb form.

This is completely normal Greek grammar, not a special exception.

Yes. Greek word order is more flexible than English because case endings show grammatical relationships.

You can say:

• Η διάγνωση καρκίνου επιβεβαιώθηκε.
• Επιβεβαιώθηκε η διάγνωση καρκίνου.

Both are grammatical. The difference is mostly one of style, focus, or emphasis.

The version you were given is a neutral, straightforward way to present the information.

Yes, it sounds fairly formal and clinical. It is the kind of sentence you might see in:

• a medical report
• a doctor’s note
• a formal discussion of test results

That is because of both:

• the vocabulary, especially διάγνωση
• the passive form επιβεβαιώθηκε

In everyday conversation, Greek speakers might use a less formal wording depending on context, but this sentence is very natural in medical or official language.

A helpful approximate pronunciation is:

thee-AHG-no-see kar-KEE-noo ee-pee-veh-veh-O-thee-keh

A slightly more accurate guide:

• διάγνωση = thi-AGH-no-si
• καρκίνου = kar-KEE-nu
• επιβεβαιώθηκε = e-pi-ve-ve-O-thi-ke

A few useful notes:

• γν in διάγνωση may feel unusual for English speakers; pronounce the γ as a soft Greek sound, not exactly like English g
• the stress falls on:
  • διάγνωση
  • καρκίνου
  • επιβεβαιώθηκε

Not exactly in structure, even though the meaning can match.

In Greek, this is literally:

• diagnosis of cancer

Greek commonly uses:

• main noun + genitive

where English often uses either:

• of
• or a noun used adjectivally, like cancer diagnosis

So a Greek learner should think of καρκίνου as a genitive phrase, not as an adjective.

The dictionary forms are:

• η διάγνωση = diagnosis
• ο καρκίνος = cancer
• επιβεβαιώνω = confirm

In the sentence, these appear as:

• η διάγνωση → unchanged in the nominative singular
• ο καρκίνος → καρκίνου in the genitive singular
• επιβεβαιώνω → επιβεβαιώθηκε in the aorist passive, 3rd person singular

This is a good example of how Greek changes word forms to show grammatical function.