Reducing inequalities with regard to illness is one of the major expected outcomes of the third Cancer Plan 2014-2019, which calls for "a reduction of the impact of cancer on personal life" so as to avoid "double punishment" (illness and exclusion from the labour market). In this context, we have assessed the impact from one to five years for a first-time registration of long-term illness characterised by cancer, on employment status and time spent in employment, sickness and unemployment for private sector employees. We have used the Hygie administrative database, mapping the professional careers and periods of illness of a sample of employees who are members of the French General Social Security Scheme. Assessment of the impact of the development of cancer is based on double difference method, with exact matching to compare ill employees with employees with no long-term illness. The first year after diagnosis equates to treatment time characterised by an increase in the number of annual quarters of sick leave, 1.7 for women and 1.2 for men. Age also plays a role in illness-related absences. Furthermore, the employability of workers with cancer decreases with time. The proportion of women and men employed for at least one quarter fell by 8 and 7 percentage points respectively in the year following the development of cancer and by up to 13 percentage points five years later. This distancing of employment increased when sick employees were older. The impact of illness on employment five years later was 15 percentage points for men aged over 51 and 19 points for women aged over 48. These differences for gender and age may reflect differences in the location and severity of the cancer, including on one hand the after-effects of cancer, and on the other greater difficulties reintegrating the labour market with increasing age.