Increasing trends in the prevalence of prior cancer in newly diagnosed lung, stomach, colorectal, breast, cervical, and corpus uterine cancer patients: a population-based study.
BACKGROUND
Cancer survivors are frequently excluded from clinical research, resulting in their omission from the development of many cancer treatment strategies. Quantifying the prevalence of prior cancer in newly diagnosed cancer patients can inform research and clinical practice. This study aimed to describe the prevalence, characteristics, and trends of prior cancer in newly diagnosed cancer patients in Japan.


METHODS
Using Osaka Cancer Registry data, we examined the prevalence, characteristics, and temporal trends of prior cancer in patients who received new diagnoses of lung, stomach, colorectal, female breast, cervical, and corpus uterine cancer between 2004 and 2015. Site-specific prior cancers were examined for a maximum of 15 years before the new cancer was diagnosed. Temporal trends were evaluated using the Cochran-Armitage trend test.


RESULTS
Among 275,720 newly diagnosed cancer patients, 21,784 (7.9%) had prior cancer. The prevalence of prior cancer ranged from 3.3% (breast cancer) to 11.1% (lung cancer). In both sexes, the age-adjusted prevalence of prior cancer had increased in recent years (P values for trend < 0.001), especially in newly diagnosed lung cancer patients. The proportion of smoking-related prior cancers exceeded 50% in patients with newly diagnosed lung, stomach, colorectal, breast, and cervical cancer.


CONCLUSIONS
The prevalence of prior cancer in newly diagnosed cancer patients is relatively high, and has increased in recent years. Our findings suggest that a deeper understanding of the prevalence and characteristics of prior cancer in cancer patients is needed to promote more inclusive clinical research and support the expansion of treatment options.
['Sato|Akira|A|', 'Matsubayashi|Keisuke|K|', 'Morishima|Toshitaka|T|', 'Nakata|Kayo|K|', 'Kawakami|Koji|K|', 'Miyashiro|Isao|I|']
D000293:Adolescent D000328:Adult D000368:Aged D000369:Aged, 80 and over D001943:Breast Neoplasms D015179:Colorectal Neoplasms D005260:Female D006801:Humans D007564:Japan D008175:Lung Neoplasms D008297:Male D008875:Middle Aged D016609:Neoplasms, Second Primary D015995:Prevalence D012042:Registries D013274:Stomach Neoplasms D002583:Uterine Cervical Neoplasms D014594:Uterine Neoplasms D055815:Young Adult
Prevalence Prior cancer Cancer survivors Cancer registry Second cancer