NZ Health Select Committee 2006 decision on Dr Muriel Newman’s 2005 petition calling for prostate cancer screening
Petition of Dr Muriel Newman and 585 others
The Health Committee recommends that the Government:
- Urgently develops a national guideline to help asymptomatic men, their families, and doctors, to making fully informed decisions about screening for prostate cancer.
- Evaluate the evidence of the two trials that are presently being conducted into whether screening can reduce the incidence of death from prostate cancer, and re-assess its policies as soon as they are completed.
The petitioner is requesting the introduction of a national prostate cancer screening programme for all “at-risk” men from the age of 40, and all other men from the age of 50.1 The petitioner also requests that the Ministry of Health change the advice on its website to recommend regular screening for prostate cancer, instead of testing only those men who experience symptoms indicating the possibility of prostate cancer.
1 This reflects the advice given by the New Zealand Prostate Cancer Foundation.
Tests and screening
Tests used to diagnose prostate cancer include a prostate specific antigen blood (PSA) test, a digital rectal examination, and a biopsy of the prostate gland. Current screening is typically carried out using the PSA test and digital examination in the first instance, followed by biopsy if necessary.
Population screening involves testing a population group to detect asymptomatic disease that may be prevented, cured, or slowed in its progression by early intervention. The evidence is that, if diagnosed and treated early, the cure rate for prostate cancer is over 90 percent.
The need for screening
The petitioner claims that a screening programme would ensure that more men were diagnosed early and treated successfully than the current policy, which relies on symptoms being present, by which time the disease is usually well advanced. The petitioner emphasises that a screening programme will also result in baseline PSA data, and men will receive valuable preventive health education.
The petitioner says many men will die unnecessarily if the ministry continues to recommend screening only those men who have symptoms when urologists advise that early diagnosis could save 300 lives annually.
Prostate cancer is the most common form of cancer in New Zealand men. The main risk factor is a family history of prostate cancer, which represents a high risk of contracting it. The petitioner asked us to consider the petition in the context of the Government’s routine screening programmes for cervical and breast cancer, and the relative incidence of these diseases.
In 2001, 189 women were diagnosed with cervical cancer and 2,310 with breast cancer, and 63 and 615 deaths respectively were attributed to these two diseases. The corresponding figures for prostate cancer in that year were 3,046 diagnoses, and 592 attributable deaths. Overall 17,913 people were diagnosed with cancer, and 7,810 people died of some form of cancer.
The petitioner considers that this implies a message that women matter and men do not. The petitioner noted the ministry’s public health campaigns about various types of cancer, such as breast and skin cancers, compares poorly with public health information about prostate cancer.
The petitioner considers that the argument against population screening based on the unreliability of PSA test results is flawed; the number of false positive tests in young women undergoing mammography for breast cancer is similar to those in men tested for prostate cancer. A similar argument was used in the debate about screening for breast cancer in young women.
However, compared with the risk of death from undetected breast and cervical cancers, the risk of mortality from prostate cancer is low, even if not detected and treated early. The risk is also high for bowel cancer and, although its incidence is not quite as high as that of prostate cancer, it is estimated that 50 percent of people affected die of it, compared with a mortality rate of three percent in undetected prostate cancer.
The ministry is convinced that early detection of bowel cancer will save lives, whereas the value of screening for prostate cancer remains uncertain, and it is therefore considering implementing a national bowel cancer screening programme.
Need for assessment
The ministry emphasised that preliminary work on screening programmes should explore all the relevant issues, such as the public acceptance of screening, cost benefits, and resource issues. Any screening programme must be researched fully and implemented properly to ensure it is cost-effective and maximises the public benefit.
Implications of population screening
Reliability of tests
The ministry says that screening using the PSA test, the most widely studied screening test, has been a controversial issue internationally for a long time. This is because no randomised study has shown any overall benefit, in terms of survival rates, in screening men who do not have symptoms.
While it is true that the PSA test detects many prostate cancers, the test is not completely reliable. Malignancy accounts for only 10 percent of cases of elevated PSA levels, the other 90 percent being due to causes such as infections, physical activity, and benign gland enlargement. Current tests are not sufficiently sensitive to decide whether an abnormal result is caused by a benign or malignant condition.
The incidence of false positive results is of concern to the ministry. PSA test results can also produce false negative results, so that cancer may not be detected even if present. A biopsy that confirms the presence of cancer will not necessarily indicate the seriousness of the cancer or the likelihood of its spreading.
The petitioner disputed the strength of the argument about unreliable results, saying that the PSA test is only one part of the screening process, and that testing by obtaining several biopsies from different parts of the prostate (in a single procedure), reduces the false negative rate to five percent and the false positive rate to zero.
The petitioner also noted that common international practice is to take a series of PSA tests over time, rather than a single test, to show any trend in elevation, before proceeding with treatment.
Effects of treatment
The ministry acknowledged that surgery or radiotherapy treatment provides good localised treatment for prostate cancer. However there is still uncertainty about the impact of treatment on survival rates, and whether early treatment of the disease is better than later treatment. The ministry is concerned that screening may lead to unnecessary tests and treatment, which can cause unnecessary anxiety and significant side-effects.
These can include sexual, bladder, or bowel dysfunction, which may be debilitating, while an undetected or untreated slow-growing cancer may never cause symptoms or shorten life. Studies show that 30 percent of men who die have undetected prostate cancer; in very elderly men the percentage is around 50 percent, with possibly 1 to 2 percent of these deaths attributable to prostate cancer.
The ministry says that, because there are no known modifiable risk factors for prostate cancer and therefore no basis for preventative strategies, the focus in recent decades has been on reducing morbidity and mortality rates through early detection and improved treatment of men with prostate cancer.
Several factors influenced the current national policy on screening (based on recommendations by the National Health Committee to the Minister of Health in April 2004): prostate cancer is largely a disease of older men, the majority of men with the disease will not die of it, and the evidence regarding outcomes from early treatment or reduced mortality rates does not conclusively support population screening.
The ministry does not therefore recommend screening men, irrespective of age, who do not have symptoms. Publicly funded PSA testing is available on request; and the ministry recommends that men are fully informed about the advantages and disadvantages of screening and possible treatment before being screened.
The petitioner believes population screening has been implemented in some states in the United States of America, and noted that in Germany all men aged 45 and older are advised to have digital rectal examinations. The ministry said that current New Zealand policy on screening for prostate cancer is consistent with policies in overseas countries country has implemented a formal population screening programme), and with World Health Organisation advice to await the results of current trials before introducing mass screening.
We were informed that randomised trials have been conducted overseas to determine whether screening programmes using PSA testing will reduce the risk of death; one has ended in late 2006 but has not been reported and the other will end in 2008. The ministry expects these results to influence policy development in New Zealand, and intends to reassess the evidence in 2008.
We were advised that these trials are the most robust trials to date and they will reduce the risk of death. We recommend that the Government evaluate the evidence of the two trials that are presently being conducted into whether screening can reduce the incidence of death from prostate cancer, and re-assess its policies as soon as they are completed.
The ministry believes that any national screening programme must be supported by substantiated evidence of better survival rates. It disagrees with the petitioner’s claim that its policy on screening for prostate cancer is largely an economic decision, although financial considerations are an essential factor in all decisions.
The ministry informed us it was developing a national guidance tool to help asymptomatic men, their families, and doctors, to make fully-informed decisions about PSA testing. The ministry was careful to distinguish between information about screening currently available on its website, which explains why a screening programme is not recommended, and information pertinent to an individual’s decision-making, and acknowledged a responsibility to avoid confusing these messages.
We recommend that the Government urgently develops a national guideline to help asymptomatic men, their families, and doctors, to making fully informed decisions about screening for prostate cancer.
This petition was carried over from the last Parliament. We received written evidence from the petitioner, the Ministry of Health, and the National Health Committee, and heard evidence from the petitioner and the Ministry of Health. We heard evidence on 3 and 10 May 2006.
Sue Kedgley (Chairperson) Maryan Street (Deputy Chairperson) Dr Jackie Blue Dr Jonathan Coleman Jo Goodhew Ann Hartley Sue Moroney Hon Tony Ryall Lesley Soper Barbara Stewart Tariana Turia
Graham Hill, Clerk of the Committee John Thomson, Parliamentary Officer, (Committee Support)