The risks of continuing to smoke after diagnosis, treatment for prostate cancer


An article just published in BJU International has further confirmed the risks associated with continuing to smoke cigarettes after initial diagnosis with, and treatment for, prostate cancer.

According to Steinberger et al., and based on their retrospective review of data from patients diagnosed with prostate cancer and treated with radiation therapy at Memorial Sloan-Kettering Cancer Center, continued (“current”) smoking significantly increased the risks of biochemical (PSA-based) relapse, distant metastases, and prostate cancer-specific mortality. This article is also discussed on the ScienceDaily web site.

Here are the core data presented by Steinberger et al.:

  • Their database contained 2,358 patients (all diagnosed between 1988 and 2005).
    • All patients were treated with external beam radiation therapy.
    • 2,156/2,358 patients (91.4 percent) had chart-recorded smoking histories.
    • The average (median) dose of radiation therapy was 81 Gy.
    • The average (median) follow-up was 95 months (i.e., about 8 years).
  • Patients were categorized into one of four groups:
    • “Never smokers”
    • “Current smokers”
    • “Former smokers”
    • “Current smoking unknown”
  • Where these data were available, study analyses included
    • Quantity of tobacco use in pack-years
    • Duration of smoking
    • How long before initiation of radiation therapy the patient quit smoking (for former smokers only)
  • Compared to data for the “never smokers”, being a “current smoker” was associated with a significant increase in
    • Risk for PSA-based disease recurrence (hazard ratio [HR] = 1.4; P = 0.02)
    • Risk for distant metastasis (HR = 2.37; P < 0.001)
    • Risk for prostate cancer-specific mortality (HR = 2.25; P < 0.001)
    • Risk for radiation-related genitourinary toxicities (HR = 1.8; P = 0.02)
  • Compared to data for the “never smokers”, being a “former smoker” was associated with a significant increase in risk for radiation-related genitourinary toxicities (HR = 1.45, P = 0.01).
  • Current or former smoking appeared to have no impact on risk for radiation-related gastrointestinal toxicities.

The authors (justifiably) concluded that physicians

should encourage [prostate cancer] patients to participate in smoking-cessation programs before [radiation] therapy to potentially lower their risk of relapsing disease and post-treatment toxicities.

This is by no means the first time that data have suggested that there is significant risk for adverse consequences associated with continuing to smoke cigarettes after a diagnosis of prostate cancer. However, these data certainly help to confirm the earlier studies.

Quoted in the report on the ScienceDaily web site, Dr. Michael Zelefsky, the study’s senior author states that:

Less optimal tumor control outcomes among smokers could possibly be explained by the influence of less oxygen concentration within the treated tumors among smokers, which is known to lead to less sensitivity of the cells being killed off by radiation treatments.

3 Responses

  1. So “Current or former smoking appeared to have no impact on risk for radiation-related gastrointestinal toxicities” doesn’t seem to mesh with what the conclusion was. That not smoking made a difference.

    It seems as if there is no difference between a current smoker and a reformed one in the study. They have the same significantly higher risk.

  2. Dear Dan:

    The fact that current or former smoking didn’t make any difference to GI toxicities doesn’t mean that current smokers didn’t have earlier recurrence, more metastases, and die sooner (which they did) compared to the never-smokers (and probably the former smokers too). I haven’t been though all of the details of the full text related to risk for the former smokers but stopping smoking did lower one’s risk for recurrence and other consequences, just not as much as if you were a “never smoker”.

    It also seems likely that how much you smoked and how long before treatment you stopped smoking would also make a difference.

  3. In view of Dan’s comment above, I went back and looked at the detailed information in the full text of this article, which states that:

    — “The 10-year likelihood of PSA relapse-free survival among current smokers, former smokers, and non-smokers were 52.4%, 62.6%, and 66.4%, respectively (P = 0.03, log-rank test).” But …
    — Compared to the never smokers, “former smokers were not found to be at increased risk for PSA relapse (HR 1.07; … P = 0.47).”
    — “the 10-year likelihood of distant metastases-free survival among current smokers, former smokers, and non-smokers was 72.2%, 85.8%, and 87.3%, respectively (P < 0.001).” But, …
    — Compared to the never smokers, "former smokers only trended toward an increase (HR 1.12, … P = 0.42).”

    In other words, stopping smoking did make a difference over a 10-year follow-up period, but it wasn’t as much as if you never started smoking in the first place (which is hardly a shock!).

    It’s also worth remembering that men (and women) who keep on smoking as they age are also at massively increased risk for a whole bunch of other reasons for an early death, including lung cancer, bladder cancer, and a variety of chronic pulmonary and cardiovascular disorders.

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