_Carcinoma_ and
_sarcoma_ agree in possessing all the pathological and cellular
features of malignant new growths.

Statistics of cancer.

Simultaneously with the active pursuit of laboratory research much
statistical work has been devoted to establishing the broad facts of the
prevalence and incidence of cancer on a firm basis. The point of most
general interest is the apparently steady increase of the disease in all
countries possessing fairly trustworthy records. It will be sufficient
to give the figures for England and Wales as an example.

ANNUAL DEATH-RATES FROM CANCER TO A MILLION LIVING. _England and
Wales._

+----------+----------+----------+----------+----------+----------+----------+
|1871-1875.|1876-1880.|1881-1885.|1886-1890.|1891-1895.|1896-1900.|1901-1904.|
+----------+----------+----------+----------+----------+----------+----------+
| 445 | 493 | 547 | 631 | 711 | 800 | 861 |
+----------+----------+----------+----------+----------+----------+----------+

In forty years the recorded rate had risen from 403 to 861. The question
how far these and similar statistics represent a real increase cannot be
satisfactorily resolved, because it is impossible to ascertain how much
of the apparent increase is due to more accurate diagnosis and improved
registration. Some of it is certainly due to those causes, so that the
recorded figures cannot be taken to represent the facts as they stand.
At the same time it is certain that some increase has taken place in
consequence of the increased average length of life; a larger proportion
of persons now reach the ages at which cancer is most frequent. Increase
due to this fact, though it is a real increase, does not indicate that
the cause of cancer is more rife or more potent; it only means that the
condition of the population in regard to age is more favourable to its
activity. On the whole it seems probable that, when allowance has been
made for this factor and for errors due to improved registration, a real
increase due to other causes has taken place, though it is not so great
as the recorded statistics would indicate.

The long-established conclusions concerning the incidence of the disease
in regard to age and sex have been confirmed and rendered more precise
by modern statistics. Cancer is a disease of old age; the incidence at
the ages of sixty-five to seventy-five is ten times greater than at the
ages thir