Do I Really Need to Quit Smoking Before Treatment? (2026 Guide)

Yes — continuing to smoke after a diagnosis is linked to higher risk of recurrence or second cancers, reduced treatment response, and increased side effects, so quitting as soon as possible is recommended. It's never too late to start.

Key Takeaways

• Continuing to smoke after diagnosis is associated with increased risk of recurrence and second cancers, reduced treatment response, and increased treatment-related side effects (U.S. National Cancer Institute, NCI).
• Cancer patients are advised to be regularly asked about their smoking status and to receive smoking cessation counseling along with medication as needed (NCI).
• A dental visit is recommended at least 2 weeks before starting immunotherapy, chemotherapy, or head and neck radiation therapy; if dental treatment is needed, a check-up about a month beforehand is advisable (NCI) — this is a separate but related pillar of pre-treatment preparation alongside quitting smoking.
• Alcohol may also increase the risk of recurrence and second cancers, so drinking before, during, and after treatment should be discussed with your care team (NCI).
• Korean hospitals advise patients who currently smoke to disclose this early in their care, and patients can receive smoking cessation counseling and supportive therapy together.

Is It Already Too Late to Quit Now?

• It's not too late. Starting to quit smoking before treatment still matters, since continuing to smoke after diagnosis is known to be associated with increased risk of recurrence or second cancers, reduced treatment response, and more treatment-related side effects (NCI).
• That's why care teams routinely ask about smoking status during pre-treatment consultations and, when needed, recommend smoking cessation counseling together with medication. Getting professional support rather than trying to quit alone can help improve your chances of success.

Besides Smoking, What Else Should Be Checked Before Treatment?

• Alcohol is often mentioned alongside smoking. Drinking may increase the risk of recurrence or second cancers, so it's best to discuss alcohol use during and after treatment with your care team (NCI).
• Maintaining your weight, getting enough protein, and exercising as much as you're able (including walking) can also help you get through treatment. Nutritional status affects both treatment outcomes and quality of life, so it is treated as an important factor (National Cancer Information Center).
• If you're scheduled for immunotherapy, chemotherapy, or head and neck radiation therapy, it's also a good idea to arrange a dental check-up. A visit at least 2 weeks before treatment starts is recommended, and if dental work is needed, a check-up about a month in advance is advised (NCI). This can help reduce or lessen the severity of oral complications during treatment.

How Is Smoking Cessation Prepared For in Korea?

• Step 1 — Disclose your smoking status at your first consultation. If you currently smoke, it's best to mention this early in your care.
• Step 2 — Receive guidance on smoking cessation counseling and, if needed, supportive therapy (such as medication).
• Step 3 — Along with your treatment schedule, check off other preparation items such as dental check-ups and nutrition counseling.
• Step 4 — Even after treatment begins, your smoking status will be checked regularly, and you'll continue cessation support throughout.

FAQ — Does Quitting Smoking Reduce Side Effects?

While no specific figures are given, continuing to smoke after diagnosis is known to be associated with increased treatment-related side effects, reduced treatment response, and higher risk of recurrence or second cancers (NCI). Conversely, quitting smoking is considered a factor that may help reduce these risks. That said, the degree of benefit can vary by individual, so it's best to work out a smoking cessation plan together with your care team.

FAQ — Should I Also Quit Drinking Along with Smoking?

Alcohol is also mentioned as a factor that may increase the risk of recurrence or second cancers (NCI). Whether you need to stop drinking entirely or whether cutting back is acceptable depends on the type of cancer, the treatment plan, and your individual condition, so the most accurate guidance is to discuss alcohol use during and after treatment directly with your care team.

Sources and Notes

• This article was written based on notes regarding pre-treatment nutrition and physical preparation (National Cancer Information Center; U.S. National Cancer Institute, NCI).
• This content is intended for general medical information purposes only. Diagnosis, treatment methods, and outcomes may vary depending on individual circumstances. Accurate diagnosis and treatment decisions should always be made in consultation with your medical team.