Translation

残念ながら / 遺憾ながら / 惜しいことに

Meaning

Regrettably means unfortunately; it says that a fact, result, or situation is bad or disappointing. It does not require anyone to feel personal regret. The trap is using regretfully when only the situation is unfortunate.

Examples

• 残念ながら、その薬はすべての患者に効くわけではありません。
  Regrettably, the drug does not work for every patient.
• 残念ながら、報告書には重要なデータが抜けていました。
  Regrettably, the report omitted important data.