Public Defence: Fei-Chih Liu

MD, MPH Fei-Chih Liu at Institute of Basic Medical Sciences will be defending the thesis “Ultraviolet exposure and night shift work in relation to risk of skin, breast and prostate cancer in offshore petroleum workers” for the degree of PhD (Philosophiae Doctor).

An electronic copy of the thesis may be ordered from the faculty up to 2 days prior to the public defence. Inquiries regarding the thesis after the public defence must be addressed to the candidate.

Trial Lecture – time and place

See Trial Lecture.

Adjudication committee

  • First opponent: Vice Dean of Research, Professor Pål Richard Romundstad, NTNU
  • Second opponent: Department Head, Professor Eva Schernhammer, Medical University of Vienna
  • Third member and chair of the evaluation committee: Department Chief Physician, Associate Professor II Ingrid Sivesind Mehlum, University of Oslo

Chair of the Defence

Associate Professor Hanne Cathrine Lie, Faculty of Medicine, University of Oslo

Principal Supervisor

Researcher Jo S. Stenehjem, Cancer Registry of Norway


PhD-candidate Fei-Chih Liu and co-workers investigated ultraviolet radiation and night shift work in relation to risk of skin, breast and aggressive prostate cancer in offshore petroleum workers.

They found that Norwegian offshore petroleum workers are at a higher risk of skin, breast and prostate cancer compared to the general population. Reasons for this could be that they differ from the average Norwegian both in terms of work and life style they pursue. Offshore workers spend two weeks offshore on platforms and have four weeks off. They work 12 hours a day, and some work nighttime. Night shift workers might have trouble with readjusting to a normal daytime schedule, which could lead to hormonal disturbance and increase the risk of breast and prostate cancer. Also, with high income and long off-duty periods, workers may engage in leisure time activities such as travelling to sunny destinations with excessive ultraviolet radiation exposure, which is a known carcinogen.

Frequent sunburns and sunscreen use were associated with higher skin cancer risk for male and female workers combined. More than 40% of the skin cancers could be attributed to ever being sunburned. Frequent indoor tanning was more specific to an increase in squamous cell carcinoma risk than melanoma risk.

Females with more than six years of night shift had higher breast cancer risk compared to those who only worked day time, but the result was not statistically significant. Males who worked night shift had over two times higher risk of breast cancer compared to the general Norwegian population.

Males who ever worked night shift had increased risk of aggressive prostate cancer compared to those who only worked daytime. This association was most evident among those with a long (>19 years) offshore career of night shift work. This work may raise awareness of cancer risk among workers employed in the Norwegian offshore petroleum industry.

Additional information

Contact the research support staff.

Published Sep. 9, 2022 10:16 AM - Last modified Sep. 22, 2022 1:44 PM