Prostate cancer survival improving among older men who have conservative management

Prostate cancer survival improving among older men who have conservative management

Older men whose localized prostated cancer is not aggressively treated with surgery or radiation but follows a conservative management regime also known as "watchful waiting" are surviving longer, according to a new US study.

These are the conclusions of Senior author Dr Grace L. Lu-Yao of the Cancer Institute of New Jersey and UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, and colleagues, in a study that is published in the September 16 issue of JAMA, the Journal of the American Medical Association.

For the study Lu-Yao and colleagues compared the survival rates of different eras of treatment for localized prostate cancer in men over 65 who following diagnosis had conservative treatment as opposed to aggressive intervention.

They found that the overall and prostate cancer-specific survival rates following conservative treatment were higher for men diagnosed beween 1992 and 2002 than they were for men diagnosed in the 1970s and 1980s.

Among American men, prostate cancer is the second most common cancer after skin cancers, and the second most common cause of death after lung cancer.

In about 85 per cent of diagnosed cases in the US, the prostate cancer is localized, that is contained within the prostate and has not yet started to spread to other organs. Standard treatment usually comprises surgery, radiation, or conservative management where the cancer is closely monitored leaving the option of more aggressive treatment still open should signs and symptoms worsen, wrote the authors.

However they found that conservative management has only been used in around 1 in 10 patients, despite its potential as a reasonable treatment option, and suggested this could be because we don't understand enough about what happens in such cases and the data is not up to date, making it difficult for doctors and patients to weigh up the pros and cons of this option. Hence the reason for the study.

Lu-Yao and colleagues analyzed data on 14,516 men who were aged 65 years or older in the period 1992 to 2002 when they were diagnosed with localized T1 and T2 prostate cancer. This is the decade when the PSA (prostate-specific antigen) test was already in use.

None of the men in the cohort had surgery or radiation for 6 months after diagnosis and more than half of them were over 78 years old when diagnosed, which makes this study unique because although men over 75 are prime candidates for conservative management, there is not enough information on this age group because they are often under-represented in studies.

(T1 and T2 are stages of prostate cancer: T1 means the tumor is very small and hard to detect by scans or when the doctor squeezes the prostate from the outside (most likely detected from a biopsy where a piece of tissue from the prostate is removed by needle and sent for testing), and T2 means the tumor(s) could be large or small but still contained in the prostate gland.)

Since the men lived in areas covered by SEER (the Surveillance, Epidemiology, and End Results program, a National Cancer Institute program that tracks cancer incidence and survival in the United States), the researchers were able to follow them for a median of 8.3 years up until December 2007.

The results showed that:

  • The 10-year rates of death due to prostate cancer was 8.3 per cent for men with well differentiated tumors, 9.1 per cent for moderately differentiated and 25.6 per cent for men with poorly differentiated tumors. (Tumors with well differentiated cells, that is where the cancer cells are clearly distinguishable from healthy cells, are the least aggressive and least likely to progress quickly).
  • The corresponding 10-year risk of dying from causes other than prostate cancer for each of these groups was 59.8 per cent, 57.2 per cent and 56.5 per cent respectively.
  • Survival results in the the "comtemporary PSA era cohort" (as the authors described the 1992 to 2002 cases they examined) were more favourable than results reported in studies relating to earlier periods.
  • For example, the 10-year rate of death due to prostate cancer for men aged 65 to 74 diagnosed with moderately differentiated tumors in the PSA era was 6 per cent, compared with 15 to 23 per cent in earlier eras (1949 to 1992).
  • Thus the 10-year rate of death due to prostate cancer for men aged 65 to 74 diagnosed with moderately differentiated tumors in the PSA era was 60 to 74 per cent lower than in earlier studies.
  • There was also a noticeable improvement in survival among men who were older or had poorly differentiated tumors.
Lu-Yao and colleagues concluded that:

"Results following conservative management of clinically localized prostate cancer diagnosed from 1992 through 2002 are better than outcomes among patients diagnosed in the 1970s and 1980s."

"This may be due, in part, to additional lead time, overdiagnosis related to PSA testing, grade migration, or advances in medical care," they suggested.

They explained that PSA testing identifies disease 6 to 13 years before it shows clinical symptoms, and thus patients diagnosed this way are likely to have survival rates 6 to 13 years longer because of this additional lead time.

By grade migration the authors were referring to evidence that shows:

"Previously documented systematic upgrading of modern tumors compared with earlier eras makes more recently graded tumors appear to have a more benign course, resulting in longer survivals."

However, this study shows that the net overall survival after conservative management is significantly better nowadays and therefore patients and their doctors may need to reconsider this option particularly in the light of recent data from trials that pre-date the PSA era that suggests aggressive intervention brings little if any benefits, said the researchers.

Lu-Yao, who is a cancer epidemiologist at CINJ and associate professor of medicine at UMDNJ-Robert Wood Johnson Medical School and of epidemiology at UMDNJ-School of Public Health, told the media that:

"The lack of solid data has often made it difficult for medical professionals to determine the most appropriate treatment and to predict patient outcomes for this population. These latest findings depict a more accurate survival outcome for the contemporary prostate patient."

She also cautioned that because the patients in the study were over 65, the results may not apply to younger men. Also, prostate patients expected to live more than ten years may need longer follow up data, she noted.

"Outcomes of Localized Prostate Cancer Following Conservative Management."

Grace L. Lu-Yao; Peter C. Albertsen; Dirk F. Moore; Weichung Shih; Yong Lin; Robert S. DiPaola; Michael J. Barry; Anthony Zietman; Michael O'Leary; Elizabeth Walker-Corkery; Siu-Long Yao.

JAMA, Vol. 302 No. 11, 1202- 1209, September 16, 2009.

Sources: JAMA and Archives Journals, The Cancer Institute of New Jersey.

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