Increasing incidence of thyroid cancer in the Nordic countries

The incidence of thyroid cancer is increasing in many countries, especially the papillary type that is the most radiosensitive type. We used the Swedish Cancer Register and NORDCAN to study the incidence of thyroid cancer during 1970-2013 using joinpoint regression analysis. The incidence increased during the whole study period in both men and women. Based on NORDCAN data, there was a statistically significant increase in the incidence of thyroid cancer in the Nordic countries during the same time period. In both women and men one joinpoint was detected in 2006. The incidence increased substantially during 2006-2013 in women; annual percentage change (APC) +6.16 % (95 % CI +3.94, +8.42 %) and in men; APC +6.84 % (95 % CI +3.69, +10.08 %). These results were similar as in the Swedish Cancer Register. Analyses based on data from the Cancer Register showed that the increasing trend in Sweden was mainly caused by thyroid cancer of the papillary type. We postulate that the whole increase cannot be attributed to better diagnostic procedures. Increasing exposure to ionizing radiation, e.g. medical CT scans, and to radiofrequency radiation (non-ionizing radiation) should be further studied as causative factors to this emerging thyroid cancer health problem.

One aspect to be studied is the increasing use of mobile phones. The antenna was previously placed at the top of the phone but is usually now placed at the bottom in smartphones. This gives higher exposure of radiofrequency radiation to the thyroid gland, see figure. A smartphone can in addition have multiple antennas.


Letter to New York Times

Ms. Margaret Sullivan, Public Editor                                       July 24, 2015

Ms. Carol Pogas, Reporter

The New York Times

Regarding: Cellphone Ordinance Puts Berkeley at Forefront of Radiation Debate

Published online July 21, 2015

Dear Ms. Sullivan and Ms. Pogas,

We have read this article in the New York Times with interest. However, there are several mistakes, and even wrong statements, on the health hazards from exposure to radiofrequency electromagnetic fields (RF-EMF) from cell phones in the article. In the following we want to correct some of the false statements.

The brain is the primary target organ for exposure to RF-EMF during the use of the handheld wireless phone. This has given concern of an increased risk for brain tumours. The carcinogenic effect of RF-EMF on humans was evaluated at a meeting during 24 – 31 May 2011 at the International Agency for Research on Cancer (IARC) at WHO in Lyon, France. One of us (LH) was part of the expert group. The Working Group categorised RF-EMF from mobile phones, and from other devices that emit similar non-ionising electromagnetic fields in the frequency range 30 kHz–300 GHz, as a Group 2B, i.e. a possible, human carcinogen (

Since then more studies have been published that strengthen the association between use of  wireless phones (mobile and cordless phones) and increased risk for brain tumours. We have performed long-term research in this area and in the following we give a short up-dated summary of our findings based on research since the 1990’s. In our publications relevant information can be found also on other studies, as well as discussions of the current scientific evidence.


Glioma is a malignant brain tumour (“brain cancer”), and the most common type is glioblastoma multiforme with a poor prognosis. We have published a statistically significant increased risk for glioma among users of both mobile and cordless phones. The risk increased with latency (time from first use of the phone) and cumulative number of hours for use. Highest risk was found in the area of the brain with highest exposure to RF-EMF. All these results are of biological relevance; that is what would be expected for a causal association. The full paper can be read here:


Meningioma is mostly a benign brain tumour and accounts for about 30 % of all intracranial tumours. The incidence is approximately 2-times higher in women than in men. No conclusive evidence of an association between use of mobile and cordless phones and meningioma was found in our study. However, taking the long latency periods that have been reported for the increased meningioma risk associated with exposure to ionizing radiation it is still too early to make a definitive risk assessment. Results for even longer latency periods of wireless phone use than in our study are desirable, see more details here:

 Acoustic neuroma:

Acoustic neuroma or Vestibular Schwannoma is a rare benign tumour in the eighth cranial nerve that leads from the inner ear to the brain. It grows slowly and does not undergo malignant transformation, but may give compression of vital brain stem centres. Tinnitus and hearing problems are usual first symptoms of acoustic neuroma. We published a clear, statistically significant, association between use of mobile and cordless phones and acoustic neuroma. The risk increased with time since first use. For use of both mobile and cordless phones the risk was highest in the longest latency group. Tumour volume increased per 100 hours of cumulative use and year of latency for wireless phones indicating tumour progression from RF-EMF. The whole study can be read here:

Brain tumour incidence:

It is not correct to claim that the incidence of brain tumours has not increased in the Scandinavian countries. The age-standardized incidence of brain tumours increased dramatically in Denmark with +41.2 % among men and +46.1 % among women during 2003-2012 ( – dansk/Sundhedsdata og it/NSF/Registre/Cancerregisteret/Cancerregisteret 2012.ashx).

Due to the well-known under-reporting of brain tumours to the Swedish Cancer Registry we studied brain tumour rates using the Swedish National Inpatient Register and the Causes of Death Register. In summary we found a statistically significant increasing rate of not specified brain tumours from 2007 in the Inpatient Register and from 2008 in the Causes of Death Register. Our study indicated that several of these tumours were never reported to the Swedish Cancer Register. Thus, the Swedish Cancer Register data cannot be used to dismiss an increased risk for brain tumours associated with use of wireless phones. On the contrary our study is consistent with an association considering a reasonable tumour induction period, see more here:

Mechanistic aspects:

It is correct that RF-EMFs do not cause direct DNA damage. On the other hand numerous studies have shown generation of reactive oxygen species (ROS) that can cause oxidative damage of DNA. This is a well-known mechanism in carcinogenesis for many agents. The broad biological potential of ROS and other free radicals makes radiofrequency radiation a potentially hazardous factor for human health, not only cancer risk but also other health effects. A recent update can be read here:


To further evaluate strengths of evidence Bradford Hill wrote in the 1960’s a famous article on association or causation at the height of the tobacco and lung cancer controversy. Hill offered a list of nine aspects of an association to be considered when deciding if an association is causal. However, he did not request all nine viewpoints to be fulfilled for causality. We used the Hill criteria to evaluate the causality on brain tumor risk from RF-EMF emitted from wireless phones. We concluded that based on the Hill criteria, glioma and acoustic neuroma should be considered to be caused by RF-EMF emissions from wireless phones and regarded as carcinogenic to humans, classifying it as Group 1 according to the IARC classification. Current guidelines for exposure need to be urgently revised. See more here:


Our results are in agreement with other studies such as the international Interphone study and the French so called CERENAT study. This is discussed in e.g. our article on glioma risk. In summary there is consistent evidence of increased risk for glioma and acoustic neuroma associated with use of mobile phones and cordless phones. Furthermore, the risk is highest for persons with first use before the age of 20, which is of special concern. Our conclusion is that RF-EMF should be regarded as a human carcinogen. The IARC classification should be updated to at least Group 2A, a probable human carcinogen. It is necessary to give the public correct information on the cancer risk. The precautionary principle should be used to minimize exposure to RF-EMF. Media have an important role to inform in a balanced way. Unfortunately this article in the New York Times is biased towards the no risk assumption. It should be corrected based on facts and not wishful thinking.


Yours sincerely,

Lennart Hardell, MD, PhD

Department of Oncology

University Hospital

SE-701 85 Örebro



Michael Carlberg, MSc

Department of Oncology

University Hospital

SE-701 85 Örebro


Increasing rate of brain tumours in Sweden

Radiofrequency fields emitted from mobile and cordless phones were in May 2011 evaluated to be ’possibly’ carcinogenic to humans, Group 2B, by IARC. This has had little effect on precaution. Instead incidence data on brain tumour from the Swedish Cancer Register have been used to dismiss the increased risk. In this study we show that these data are not reliable. Instead there is an increasing rate of brain tumours in Sweden. Using the Swedish National Inpatient we show in this study that the rate of brain tumours in Sweden increased since 2007. This increase was seen from 2008 in the Causes of Death Register. The increasing rates may be caused by use of mobile and cordless phones, see

Sharp increase in patients treated for brain tumors with unclear diagnosis in Sweden

An increasing number of patients are treated for brain tumor ”of unknown nature” in Sweden since 2008, but the increase is not reflected in the national cancer registry, according to the Swedish Radiation Protection Foundation. ” It is serious if the statistics on new cases of brain tumors is incorrect because the brain tumor statistics is widely being used as an argument that cell phones do not increase the risk of cancer and brain tumors” according to Mona Nilsson, Chairman of Swedish Radiation Protection Foundation.

Swedish Radiation Protection Foundation has compiled statistics from the Swedish Health Board registry’s database on the number of patients treated for brain tumors in Sweden as well as from the cancer registry and cause of death registry, during the last decade. The number of people receiving treatment for a brain tumor ”of unknown nature” increased by almost 30% only between 2008 and 2012. At the same time, the number of patients with a confirmed brain tumor diagnosis remained at a relatively stable level.

Read more:

Increasing incidence of brain tumours in Denmark

Statens Serum Institut in Denmark released recently cancer data for 2012. Of interest is the sharp increase in the incidence of brain tumours during 2003 to 2012. In men the increase was 41.2 % and in women 46.1 %. The sharp increase can not be only explained by improved diagnosis. The use of wireless phones (mobile and cordless phones) has increased since the 1990’s so the increasing incidence of brain tumour may reflect that giving a reasonable latency time of about 10 years (time from first use until diagnosis).

Incidence, brain tumours, Denmark 2003-2012

Cancer Statistics in Korea: Incidence, Mortality, Survival and Prevalence in 2010

This is the title of a recent paper from Korea on national cancer statistics during 1999 to 2010. During that period the annual increase in the incidence of all cancer was 3.3 % (p<0.05) in both sexes. Some cancer types showed a declining trend whereas the incidence increased for others.

Notably a high increasing incidence of thyroid cancer was seen both in men and women, annually 24.8 % and 24.2 % respectively.

The incidence of tumours in the brain and nervous system increased annually 1.0 % (p<0.05) in men and 0.5 % in women. For both genders together the annual incidence increase was 0.8 % (p<0.05).

The article does not discuss the causes for the different cancer pattern over the years. Certain persons claim that there is no change in the incidence of brain tumours and thus use of wireless phones is not a risk factor. This article verifies that such statements are not correct.

New ecological study on the penetration of cellular telecommunications subscriptions shows a clear association with the higher incidence of brain and nervous system tumours

The incidence of brain tumours is increasing in several countries. In spite of that some scientists claim that based on these findings it is unlikely that the use of wireless telephones (mobile phones and cordless phones; DECT) gives and increased risk of brain tumours.

Interestingly, a new recently published study based on open-access databases finds that the only exogenous risk factor consistently associated with higher incidence of brain and nervous system tumours is the penetration rate of mobile phone subscriptions. These ecological results show latency between exposure and clinical onset of the disease of at least 11-12 years, but probably more than 20 years.

The findings are in accordance with the results by the Hardell group in Sweden and the WHO Interphone study on use of wireless phones (cordless phones not included in Interphone) and the risk of brain tumours. Using 10 years or more latency a statistically significantly increased risk was found for glioma and acoustic neuroma, types of brain tumours. An overview of these findings was recently published by the Hardell group.